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Sample records for beijing electron-positron collider

  1. Prospects for the study of gluonic states at Beijing Electron- Positron Collider (BEPC)

    Energy Technology Data Exchange (ETDEWEB)

    Chanowitz, M.S.

    1989-01-11

    Progress in the study of gluonic states depends crucially on accumulating data samples of order 10/sup 8/ J//psi/ decays, in order to perform complete partial wave analyses of radiative and hadronic J//psi/ decays. This requirement is well matched to the capabilities of the Beijing Electron-Positron Collider, which has approached the necessary luminosity in its first two months of operation. 28 refs., 1 fig., 1 tab.

  2. Prospects for the study of gluonic states at Beijing Electron- Positron Collider (BEPC)

    International Nuclear Information System (INIS)

    Progress in the study of gluonic states depends crucially on accumulating data samples of order 108 J//psi/ decays, in order to perform complete partial wave analyses of radiative and hadronic J//psi/ decays. This requirement is well matched to the capabilities of the Beijing Electron-Positron Collider, which has approached the necessary luminosity in its first two months of operation. 28 refs., 1 fig., 1 tab

  3. Online beam energy measurement of Beijing electron positron collider II linear accelerator

    Science.gov (United States)

    Wang, S.; Iqbal, M.; Liu, R.; Chi, Y.

    2016-02-01

    This paper describes online beam energy measurement of Beijing Electron Positron Collider upgraded version II linear accelerator (linac) adequately. It presents the calculation formula, gives the error analysis in detail, discusses the realization in practice, and makes some verification. The method mentioned here measures the beam energy by acquiring the horizontal beam position with three beam position monitors (BPMs), which eliminates the effect of orbit fluctuation, and is much better than the one using the single BPM. The error analysis indicates that this online measurement has further potential usage such as a part of beam energy feedback system. The reliability of this method is also discussed and demonstrated in this paper.

  4. The Beijing electron-positron collider and its second phase construction

    International Nuclear Information System (INIS)

    As a powerful tool for research on the micro-world, colliders have played an essential role in the exciting discovery of particle physics in the past 30 years, and continue to serve as the dominant machines for high energy physics research. Aiming at τ and charm physics, the Beijing Electron-Positron Collider (BEPC) has become a leading machine in the world in its energy region. Many important results in high energy physics and synchrotron radiation research have been obtained with the BEPC. To maintain China's leading positron in τ and charm physics, Chinese scientists proposed the BEPC II project as the second phase construction, and this was approved by the Chinese government at the end of 2003. As with the BEPC, BEPC II will serve two purposes, i.e. research on high energy physics and synchrotron radiation. The luminosity of BEPC II will be two orders of magnitude higher than the present BEPC, and its synchrotron radiation operation will also be significantly improved. The performance of BEPC and progress in the construction of BEPC II as well as their prospects are reviewed. (author)

  5. Phasing system for the Injector of Beijing Electron Positron Collider (BEPC)

    International Nuclear Information System (INIS)

    The Injector of Beijing Electron Positron Collider is a 1.4 Gev. Electron Linear Accelerator. The sixteen klystrons and their energy doublers are used to provide microwave accelerating power for electron (or positron) beam. In order to make the energy of the accelerated electron beam maximum and the energy spectrum width minimum, every klystron must be phased to make the crests of the RF traveling wave in the accelerator coincide with the electron bunch centers. A phasing system has been designed and built in the BEPC Injector. The system is based on the beam induction technique. The heterodyne technique is used to process signals and to do phase discrimination. The step motor-driven phase shifters (FOX phase shifter) are used to shift the phases of klystrons. A single board microcomputer is used to provide programme control for the system. The system can phase every klystron automatically or manually and can manually shift the phase of any klystron as operator likes. The system can be operated by operator at Central Control Room, Injector Control Room or Local Panel. The system has been installed well in the klystron gallery of BEPC Injector. In order to leave over the possibility improving the system in the future, 17 equal length phase stable cables are used to be reference signal cable and phase sample cables

  6. Forty years of acting electron-positron colliders

    International Nuclear Information System (INIS)

    Around forty years passed from the beginning of operation of the first electron-positron colliding beam facility VEPP-2 in Institute of Nuclear Physics (INP), Novosibirsk. Historical aspects of development of electron-positron colliding beam project in INP as well as advance of similar projects of the first generation at LAL, Orsay and at LNF, Frascati are considered

  7. TRISTAN, electron-positron colliding beam project

    International Nuclear Information System (INIS)

    In this report e+e- colliding beam program which is now referred to as TRISTAN Project will be described. A brief chronology and outline of TRISTAN Project is given in Chapter 1. Chapter 2 of this article gives a discussion of physics objectives at TRISTAN. Chapter 3 treats the overall description of the accelerators. Chapter 4 describes design of each of the accelerator systems. In Chapter 5, detector facilities are discussed in some detail. A description of accelerator tunnels, experimental areas, and utilities are given in Chapter 6. In the Appendix, the publications on the TRISTAN Project are listed. (author)

  8. Bruno Touschek, from Betatrons to Electron-positron Colliders

    CERN Document Server

    Bernardini, Carlo; Pellegrini, Claudio

    2015-01-01

    Bruno Touschek's life as a physicist spanned the period from World War II to the 1970s. He was a key figure in the developments of electron-positron colliders, storage rings, and gave important contributions to theoretical high energy physics. Storage rings, initially developed for high energy physics, are being widely used in many countries as synchrotron radiation sources and are a tool for research in physics, chemistry, biology environmental sciences and cultural heritage studies. We describe Touschek's life in Austria, where he was born, Germany, where he participated to the construction of a betatron during WWII, and Italy, where he proposed and led to completion the first electron-positron storage ring in 1960, in Frascati. We highlight how his central European culture influenced his life style and work, and his main contributions to physics, such as the discovery of the Touschek effect and beam instabilities in the larger storage ring ADONE.

  9. DEPFET detectors for future electron-positron colliders

    International Nuclear Information System (INIS)

    The DEPFET Collaboration develops highly granular, ultra-thin pixel detectors for outstanding vertex reconstruction at future electron-positron collider experiments. A DEPFET sensor, by the integration of a field effect transistor on a fully depleted silicon bulk, provides simultaneous position sensitive detector capabilities and in pixel amplification. The characterization of the latest DEPFET prototypes has proven that a adequate signal-to-noise ratio and excellent single point resolution can be achieved for a sensor thickness of 50 micrometers. The close to final auxiliary ASICs have been produced and found to operate a DEPFET pixel detector of the latest generation with the required read-out speed. A complete detector concept is being developed for the Belle II experiment at the new Japanese super flavor factory. DEPFET is not only the technology of choice for the Belle II vertex detector, but also a prime candidate for the ILC. Therefore, in this contribution, the status of DEPFET R and D project is reviewed in the light of the requirements of the vertex detector at a future electron-positron collider

  10. Beijing Electron Positron Collider (BEPC) project

    International Nuclear Information System (INIS)

    BEPC is China's first high energy accelerator project which is being built to serve the dual purposes of carrying out particle physics studies on one hand and conducting synchrotron radiation experiments on the other. This project was formally approved at the end of 1983, and is scheduled to be completed at the end of 1988. Construction is in full swing. A brief account of the design, progress, and management of the project is presented

  11. New fast beam profile monitor for electron-positron colliders.

    Science.gov (United States)

    Bogomyagkov, A V; Gurko, V F; Zhuravlev, A N; Zubarev, P V; Kiselev, V A; Meshkov, O I; Muchnoi, N Yu; Selivanov, A N; Smaluk, V V; Khilchenko, A D

    2007-04-01

    A new fast beam profile monitor has been developed at the Budker Institute of Nuclear Physics. This monitor is based on the Hamamatsu multianode photomultiplier with 16 anode strips and provides turn-by-turn measurement of the transverse beam profile. The device is equipped with an internal memory, which has enough capacity to store 131,072 samples of the beam profile. The dynamic range of the beam profile monitor allows us to study turn-by-turn beam dynamics within the bunch charge range from 1 pC up to 10 nC. Using this instrument, we have investigated at the VEPP-4M electron-positron collider a number of beam dynamics effects which cannot be observed by other beam diagnostics tools. PMID:17477653

  12. Future electron-positron colliders and the 4-dimensional composite Higgs model

    Energy Technology Data Exchange (ETDEWEB)

    Barducci, D. [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Curtis, S. De [INFN, Sezione di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Moretti, S. [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Particle Physics Department, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Pruna, G.M. [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

    2014-02-03

    In this note we analyse the prospects of a future electron-positron collider in testing a particular realisation of a composite Higgs model encompassing partial compositeness, namely, the 4-Dimensional Composite Higgs Model. We study the main Higgs production channels for three possible energy stages and different luminosity options of such a machine and confront our results to the expected experimental accuracies in the various Higgs decay channels accessible herein and, for comparison, also at the Large Hadron Collider.

  13. Science and technology of the TESLA electron-positron linear collider

    CERN Document Server

    Wagner, A

    2002-01-01

    Recent analyses of the long term future of particles physics in Asia, Europe, and the U.S.A. have led to the consensus that the next major facility to be built to unravel the secrets of the microcosms is an electron-positron linear collider in the energy range of 500 to 1000 GeV. This collider should be constructed in an as timely fashion as possible to overlap with the Large Hadron Collider, under construction at CERN. Here, the scientific potential and the technological aspects of the TESLA projects, a superconducting collider with an integrated X-ray laser laboratory, are summarised. (1 refs).

  14. LEP : the Large Electron Positron Collider Conference MT17

    CERN Multimedia

    2001-01-01

    LEP was CERN's flagship research facility from 1989 until 2000 when it stepped aside to make way for installation of the Laboratory's next major accelerator, the Large Hadron Collider, LHC. With a circumference of 27 kilometres, LEP was the largest circular particle collider in the world. Inside its beam pipe, about 100 metres underground, bunches of electrons and positrons raced around in opposite directions as they were accelerated to almost the speed of light. In its first phase of operation, LEP was designed to collide electrons and positrons at an energy of around 100 GeV. After some seven years of accumulating data at this energy to study the Z particle - electrically neutral carrier of the weak interaction - everything was done to boost the energy of LEP's beams as high as possible.

  15. Alternate approaches to future electron-positron linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Loew, G.A. [Stanford Univ., CA (United States). Stanford Linear Accelerator Center

    1998-07-01

    The purpose of this article is two-fold: to review the current international status of various design approaches to the next generation of e{sup +}e{sup {minus}} linear colliders, and on the occasion of his 80th birthday, to celebrate Richard B. Neal`s many contributions to the field of linear accelerators. As it turns out, combining these two tasks is a rather natural enterprise because of Neal`s long professional involvement and insight into many of the problems and options which the international e{sup +}e{sup {minus}} linear collider community is currently studying to achieve a practical design for a future machine.

  16. Beam Dump Experiment at Future Electron-Positron Colliders

    OpenAIRE

    Shinya Kanemura; Takeo Moroi; Tomohiko Tanabe

    2015-01-01

    We propose a new beam dump experiment at future colliders with electron ($e^-$) and positron ($e^+$) beams, BDee, which will provide a new possibility to search for hidden particles, like hidden photon. If a particle detector is installed behind the beam dump, it can detect the signal of in-flight decay of the hidden particles produced by the scatterings of $e^\\pm$ beams off materials for dumping. We show that, compared to past experiments, BDee (in particular BDee at $e^+e^-$ linear collider...

  17. Beam dump experiment at future electron-positron colliders

    Science.gov (United States)

    Kanemura, Shinya; Moroi, Takeo; Tanabe, Tomohiko

    2015-12-01

    We propose a new beam dump experiment at future colliders with electron (e-) and positron (e+) beams, BDee, which will provide a new possibility to search for hidden particles, like hidden photon. If a particle detector is installed behind the beam dump, it can detect the signal of in-flight decay of the hidden particles produced by the scatterings of e± beams off materials for dumping. We show that, compared to past experiments, BDee (in particular BDee at e+e- linear collider) significantly enlarges the parameter region where the signal of the hidden particle can be discovered.

  18. Higgs Physics at the CLIC Electron-Positron Linear Collider

    CERN Document Server

    Roloff, Philipp Gerhard

    2016-01-01

    The Compact Linear Collider (CLIC) is an option for a future $e^+e^-$ collider operating at centre-of-mass energies up to 3 TeV, providing sensitivity to a wide range of new physics phenomena and precision physics measurements at the energy frontier. This paper presents the Higgs physics reach of CLIC operating in three energy stages, $\\sqrt{s} =$ 350 GeV, 1.4 TeV and 3 TeV. The initial stage of operation allows the study of Higgs boson production in Higgsstrahlung ($e^+e^-\\to ZH$) and $WW$-fusion ($e^+e^-\\to H\

  19. CERN: TeV Electron-Positron Linear Collider Studies; More polarization in LEP

    International Nuclear Information System (INIS)

    The world's highest energy electronpositron collider - CERN's LEP, with a circumference of 27 kilometres - will also be the last such machine to be built as a storage ring. With interest growing in electronpositron physics at energies beyond those attainable at LEP, the next generation of electron-positron colliders must be linear if prohibitive synchrotron radiation power losses are to be avoided. Very high energy linear colliders present many technical challenges but mastery of SLC at Stanford, the world's first electron-positron linear collider, is encouraging. The physics issues of a linear collider have been examined by the international community in ICFA workshops in Saariselka, Finland (September 1991) and most recently in Hawaii (April 1993). The emerging consensus is for a collider with an initial collision energy around 500 GeV, and which can be upgraded to over 1 TeV. A range of very different collider designs are being studied at Laboratories in Europe, the US, Japan and Russia. Following the report of the 1987 CERN Long Range Planning Committee chaired by Carlo Rubbia, studies for a 2 TeV linear collider have progressed at CERN alongside work towards the Laboratory's initial objective - the LHC high energy proton-proton collider in the LEP tunnel

  20. High luminosity, electron-positron colliders as strangeness, charm, and beauty factories

    International Nuclear Information System (INIS)

    This paper reports on high luminosity electron-positron colliders operating at the mass of the φ meson (1.02 GeV) that can produce copious K bar K0 pairs from a single quantum state. Temporal correlations in the decays of the K's provide a measure of the direct CP violating amplitude and also allow a high precision test of CPT invariance. A low energy collider with high luminosity can serve as a beam physics testbed to evaluate novel approaches to collider design that may be necessary for B factories to attain luminosities ≥ 1024 cm-2s-1

  1. Higgs Physics at the CLIC Electron-Positron Linear Collider

    CERN Document Server

    Abramowicz, H; Afanaciev, K; Tehrani, N Alipour; Balázs, C; Benhammou, Y; Benoit, M; Bilki, B; Blaising, J -J; Boland, M J; Boronat, M; Borysov, O; Božović-Jelisavčić, I; Buckland, M; Bugiel, S; Burrows, P N; Charles, T K; Daniluk, W; Dannheim, D; Dasgupta, R; Demarteau, M; Gutierrez, M A Díaz; Eigen, G; Elsener, K; Felzmann, U; Firlej, M; Firu, E; Fiutowski, T; Fuster, J; Gabriel, M; Gaede, F; García, I; Ghenescu, V; Goldstein, J; Green, S; Grefe, C; Hauschild, M; Hawkes, C; Hynds, D; Idzik, M; Kačarević, G; Kalinowski, J; Kananov, S; Klempt, W; Kopec, M; Krawczyk, M; Krupa, B; Kucharczyk, M; Kulis, S; Laštovička, T; Lesiak, T; Levy, A; Levy, I; Linssen, L; Lukić, S; Maier, A A; Makarenko, V; Marshall, J S; Mei, K; Milutinović-Dumbelović, G; Moroń, J; Moszczyński, A; Moya, D; Münker, R M; Münnich, A; Neagu, A T; Nikiforou, N; Nikolopoulos, K; Nürnberg, A; Pandurović, M; Pawlik, B; Codina, E Perez; Peric, I; Petric, M; Pitters, F; Poss, S G; Preda, T; Protopopescu, D; Rassool, R; Redford, S; Repond, J; Robson, A; Roloff, P; Ros, E; Rosenblat, O; Ruiz-Jimeno, A; Sailer, A; Schlatter, D; Schulte, D; Shumeiko, N; Sicking, E; Simon, F; Simoniello, R; Sopicki, P; Stapnes, S; Ström, R; Strube, J; Świentek, K P; Szalay, M; Tesař, M; Thomson, M A; Trenado, J; Uggerhøj, U I; van der Kolk, N; van der Kraaij, E; Pinto, M Vicente Barreto; Vila, I; Gonzalez, M Vogel; Vos, M; Vossebeld, J; Watson, M; Watson, N; Weber, M A; Weerts, H; Wells, J D; Weuste, L; Winter, A; Wojtoń, T; Xia, L; Xu, B; Żarnecki, A F; Zawiejski, L; Zgura, I -S

    2016-01-01

    The Compact Linear Collider (CLIC) is an option for a future e+e- collider operating at centre-of-mass energies up to 3 TeV, providing sensitivity to a wide range of new physics phenomena and precision physics measurements at the energy frontier. This paper presents the Higgs physics reach of CLIC operating in three energy stages, sqrt(s) = 350 GeV, 1.4 TeV and 3 TeV. The initial stage of operation allows the study of Higgs boson production in Higgsstrahlung (e+e- -> ZH) and WW-fusion (e+e- -> Hnunu), resulting in precise measurements of the production cross sections, the Higgs total decay width Gamma_H, and model-independent determinations of the Higgs couplings. Operation at sqrt(s) > 1 TeV provides high-statistics samples of Higgs bosons produced through WW-fusion, enabling tight constraints on the Higgs boson couplings. Studies of the rarer processes e+e- -> ttH and e+e- -> HHnunu would allow measurements of the top Yukawa coupling and the Higgs boson self-coupling. This paper presents detailed studies of...

  2. New heavy charged leptons at future high energy electron-positron colliders

    OpenAIRE

    Almeida Jr., F. M. L.; Coutinho, Y. A.; Simoes, J. A. Martins; Wulck, S.; Vale, M. A. B. do

    2003-01-01

    New heavy charged lepton production and decay signatures at future electron-positron colliders are investigated at $\\sqrt {s}=500$ GeV. The consequences of model dependence for vector singlets and vector doublets are studied. Distributions are calculated including hadronization effects and experimental cuts that suppress the standard model background. The final state leptonic energy distributions are shown to give a very clear signature for heavy charged leptons.

  3. Future Electron-Positron Colliders and the 4-Dimensional Composite Higgs Model

    OpenAIRE

    Barducci, D.; De Curtis, S.; Moretti, S; Pruna, G. M.

    2013-01-01

    In this note we analyse the prospects of a future electron-positron collider in testing a particular realisation of a composite Higgs model encompassing partial compositeness, namely, the 4-Dimensional Composite Higgs Model. We study the main Higgs production channels for three possible energy stages and different luminosity options of such a machine and confront our results to the expected experimental accuracies in the various Higgs decay channels accessible herein and, for comparison, also...

  4. Status and prospects of VEPP-2000 electron-positron collider

    Science.gov (United States)

    Rogovsky, Yu. A.; Berkaev, D. E.; Zemlyansky, I. M.; Zharinov, Yu. M.; Kasaev, A. S.; Koop, I. A.; Kyrpotin, A. N.; Lysenko, A. P.; Perevedentsev, E. A.; Prosvetov, V. P.; Romanov, A. L.; Senchenko, A. I.; Skrinsky, A. N.; Shatunov, P. Yu.; Shatunov, Yu. M.; Shwartz, D. B.

    2014-09-01

    High energy physics experiments were started at VEPP-2000 at the end of 2010; the third experimental run was finished in July 2013. The last run was devoted to the energy range 160-510 MeV in a beam. Compton backscattering energy measurements were used for the regular energy calibration of the VEPP-2000, together with resonance depolarization and NMR methods. The conception of the round colliding beam lattice along with precise orbit and lattice correction yielded a record high peak luminosity of 1.2 × 1031 cm-2 s-1 at 510 MeV and an average luminosity of 0.9 × 1031 cm-2 s-1 per run. A total betatron tune shift of 0.174 was achieved at 392.5 MeV. This corresponds to the beam-beam parameter ξ = 0.125 in terms of the collision point. The injection system is currently modernized to allow injection of particles at the VEPP-2000 energy maximum and the elimination of the existing lack of positrons.

  5. Beam-beam interaction in high energy linear electron-positron colliders

    International Nuclear Information System (INIS)

    The interaction of high energy electron and positron beams in a linear collider has been investigated using a macroparticle Monte Carlo method based on a Cloud-In-Cells plasma simulation scheme. Density evolutions, luminosities, energy and angular distributions for electrons (positrons) and synchrotron photons are calculated. Beside beams with a symmetric transverse profile also flat beams are considered. A reasonably good agreement to alternative computer calculations as well as to an analytical approximation for the energy spectrum of synchrotron photons has been obtained. (author)

  6. Environmental assessment for the proposed B-Factory (Asymmetric Electron Positron Collider)

    Energy Technology Data Exchange (ETDEWEB)

    1993-11-01

    This document presents the potential environmental consequences associated with the construction and operation of an Asymmetric Electron Positron Collider, also known as a B-Factory. DOE proposes to modify either the existing Positron-Electron Project at the Stanford Linear Accelerator Center (SLAC) or the Cornell Electron Storage Ring (CESR) at Cornell University. PEP and CESR provide the most technically promising and practical options for a B-Factory. A B-Factory can be constructed by modifying the existing facilities and with minor or no conventional construction. Details involved with the upgrade along with two alternatives to the proposed action are described.

  7. On the possibility of construction of super-high energy electron-positron colliding beam facility

    International Nuclear Information System (INIS)

    A possibility for construction of an electron-positron linear collider (EPLC) is considered. A general scheme of the facility is described where 2x1 km long linear accelerators supplied by RF powerful sources placed at the distance of about 10 m from each other ''shoot'' towards each other by single bunches of electrons and positrons with the frequency of the order of 10 Hz. Problems dealing with electrodynamics of an accelerating structure and acceleration process are considered. Peculiar features of experiments on the EPLC are described. Approximate parameters of the EPLC at the energy of 2x100 and 2x3O0 GeV are given

  8. Phenomenology of the Georgi-Machacek model at future electron-positron colliders

    CERN Document Server

    Chiang, Cheng-Wei; Yagyu, Kei

    2015-01-01

    We study the phenomenology of the exotic Higgs bosons in the Georgi-Machacek model at future electron-positron colliders such as the International Linear Collider (ILC), assuming the collision energies of 500~GeV and 1~TeV. We show that the existence of the neutral and singly-charged Higgs bosons in the 5-plet representation under the custodial $SU(2)_V$ symmetry can be readily identified by studying various energy and invariant mass distributions of the $W^+W^-Z$ final state. Moreover, their masses can be determined with sufficiently high precision to test the mass degeneracy, a feature due to the custodial symmetry of the model. A synergy between such searches at the ILC and the doubly-charged Higgs search at the LHC will make the 5-plet Higgs boson study more comprehensive.

  9. Investigation of induced radioactivity in the CERN Large Electron Positron collider for its decommissioning

    CERN Document Server

    Silari, Marco

    2004-01-01

    The future installation of the Large Hadron Collider in the tunnel formerly housing the Large Electron Positron collider (LEP) required the dismantling of the latter after 11-year operation. As required by the French legislation, an extensive theoretical study was conducted before decommissioning to establish the possible activation paths both in the accelerator and in the four experiments (L3, ALEPH, OPAL and DELPHI) installed around the ring. The aim was to define which areas may contain activated material and which ones would be completely free of activation. The four major sources of activation in LEP, i.e., distributed and localized beam losses, synchrotron radiation and the super-conducting RF cavities, were investigated. Conversion coefficients from unit lost beam power to induced specific activity were established for a number of materials. A similar study was conducted for the four experiments, evaluating the four potential sources of induced radioactivity, namely e**+e **- annihilation events, two-p...

  10. Tau reconstruction methods at an electron-positron collider in the search for new physics

    Science.gov (United States)

    Li, Jinmian; Williams, Anthony G.

    2016-04-01

    By exploiting the relatively long lifetime of the tau lepton, we propose several novel methods for searching for new physics at an electron-positron collider. We consider processes that involve final states consisting of a tau lepton pair plus two missing particles. The mass and spin of the new physics particles can be measured in 3-prong tau decays. The tau polarization, which reflects the coupling to new physics, can be measured from the τ →π ν decay channel using the impact parameter distribution of the charged pion. We also discuss the corresponding backgrounds for these measurements, the next-to-leading order (NLO) effects, and the implications of finite detector resolution.

  11. Study of single top production at high energy electron positron colliders

    International Nuclear Information System (INIS)

    The effect of single top production on the study of top quark pair production in future high energy electron-positron colliders is evaluated. The rate of the single top quark production process is sizeable throughout a large range of center-of-mass energies and the final state cannot easily be distinguished from the dominant pair production process. We discuss the impact on the top quark mass extraction from a scan through the pair production threshold and the determination of top quark form factors in the continuum. These results advocate for the exploration of the inclusive e+e- → W+bW- anti b process, that includes both top quark pair and single top quark production. (orig.)

  12. Radiation problems in the design of the large electron-positron collider (LEP)

    International Nuclear Information System (INIS)

    This is a comprehensive review of the radiation problems taken into account in the design studies for the Large Electron-Positron collider (LEP) now under construction at CERN. It provides estimates and calculations of the magnitude of the most important hazards, including those from non-ionizing radiations and magnetic fields as well as from ionizing radiation, and describes the measures to be taken in the design, construction, and operation to limit them. Damage to components is considered as well as the risk to people. More general explanations are given of the physical processes and technical parameters that influence the production and effects of radiation, and a comprehensive bibliography provides access to the basic theories and other discussions of the subject. The report effectively summarizes the findings of the Working Group on LEP radiation problems and parallels the results of analogous studies made for the previous large accelerator. The concluding chapters describe the LEP radiation protection system, which is foreseen to reduce doses far below the legal limits for all those working with the machine or living nearby, and summarize the environmental impact. Costs are also briefly considered. (orig.)

  13. Colliding. gamma. e- and. gamma gamma. -beams on the basis of electron-positron linear colliders

    Energy Technology Data Exchange (ETDEWEB)

    Ginzburg, I.F.; Kotkin, G.L.; Serbo, V.G.; Tel' nov, V.I.

    1983-08-01

    Main properties of the ..gamma..e and ..gamma gamma.. collisions are discussed in some detail with application to the generation of colliding ..gamma..e and ..gamma gamma.. beams basing on the designed linear accelerators with colliding e/sup +/e/sup -/ beams, VLEEP and SLC, as it was proposed in a previous work. Intensive ..gamma.. beams with the energy 50 GeV would be produced from scattering of the laser light focused to the electron beams of the accelerators. Laser radiation is focused to the electron beam in the conversion region at a distance of about 10 cm from the place of collision. After scattering on electrons high-energy photons move practically along the electron primary trajectories and are focused in the collision region. The electrons are deflected from the collision region by means of approximately 1 T magnetic field. Then the produced ..gamma..-beam collides with an electron beam or a similar ..gamma..-beam. In the case when the maximum luminosity (L) is attained, the luminosity distribution in the invariant mass of the ..gamma..e or ..gamma gamma.. systems is wide. A monochromatization of the collisions up to the level of 5-10% is possible. That will entail a decrease in the luminosity, the procedure is most effective if one uses the electrons and the laser photons with opposite helicities. Examples of physically interesting problems to be investigated with the proposed ..gamma..e and ..gamma gamma.. beams are suggested.

  14. Use of intersecting lasers in the alignment of the new electron-positron collider at the Stanford Linear Accelerator Center

    International Nuclear Information System (INIS)

    At the Stanford Linear Accelerator Center (SLAC) a new project is underway to build an electron-positron collider, the Stanford Linear Collider (SLC). This paper gives an overview of the alignment procedure for this project, followed by a detailed description of the first step in the alignment. In this part of the procedure pedestals are set in pitch and yaw and brought into +-3 mm of their final three-dimensional position by use of two intersecting laser beams. The fixturing and instrumentation are described, together with the software and data-flow which are used. Finally, the results obtained with this method are discussed, and conclusions are drawn on its effectiveness

  15. Limits on the brane fluctuations mass and on the brane tension scale from electron-positron colliders

    OpenAIRE

    Alcazar, J; Ruiz Cembranos, José Alberto; Dobado González, Antonio; López Maroto, Antonio

    2002-01-01

    In the context of the brane-world scenarios with compactified large extra dimensions, we study the production of the possible massive brane oscillations (branons) in electron-positron colliders. We compute their contribution to the electroweak gauge bosons decay width and to the single-photon and single-Z processes. With LEP-I results and assuming non observation at LEP-II, we present exclusion plots for the brane tension $\\tau = f^4$ and the branon mass $M$. Prospects for the next generation...

  16. Addendum to a proposal to build a 14 GeV electron-positron colliding beam facility - EPIC

    International Nuclear Information System (INIS)

    'A Proposal to Build a 14 GeV Electron-Positron Colliding Beam Facility - EPIC'; RL-74-100 was published in September 1974. Since that time, several important improvements have been made to the original concept. This Addendum to the Proposal describes the current EPIC design for electron-positron operation including those improvements. One striking change is that the main ring has be re-sited to encircle the present buildings of the Laboratory. A less obvious but nevertheless major change is an improved method of fitting positrons into the main ring. Where there were areas of uncertainty in the original calculations, a conservative approach was adopted in formulating the Proposal. In the light of further studies, it has proved possible to improve the performance of the machine at higher energies without increasing the installed RF power. With 4 MW of radio-frequency power installed, the machine is designed to reach 32 GeV centre-of-mass energy with the luminosity reaching a peak at 29.5 GeV. With the addition of a further 4 MW of power 42 GeV centre-of-mass energy is obtained. A larger vertical beam size can be accommodated without changing the original magnet aperture, allowing possible coupling effects to take place without beam loss. As in the Proposal, the machine is designed to allow the addition of a proton ring at a later date. The strong physics case for EPIC, outlined in the Proposal, is not repeated here. The arguments have been even further enhanced by the discovery of the new psi particles at Brookhaven and SLAC, - work which has received world-wide recognition as a major advance in physics, and which calls for future exploitation using a higher energy electron-positron storage ring. (author)

  17. Radiation levels in the CERN Large Electron Positron collider during the LEP 2 phase (68 105 GeV)

    Science.gov (United States)

    Gaborit, J. C.; Silari, M.; Ulrici, L.

    2006-09-01

    The CERN Large Electron Positron (LEP) collider was in operation from 1989 to 2000. At the end of 1995 the LEP 2 phase began, with the progressive upgrade of the collider energy above the W pair production threshold, until the final energy of 105 GeV per beam. During the 11-year operation an extensive radiation survey program monitored the dose levels inside and around the installation. The radiation levels monitored in the underground areas and on the surface during 1989-1995 (LEP 1 phase) were discussed in a previous paper. The aim of this paper is to complete the data reported earlier. This paper first gives an overview of the radiation levels in the LEP tunnel and in other underground areas, and then discusses measurements of the photon radiation performed in the machine tunnel at each energy increase. An estimate of neutron sources, measurements of radiation streaming through ducts and shafts and some results of measurements of synchrotron radiation from the wigglers are given next. Residual dose rates are then briefly addressed. Finally, an overview is provided of the radiation levels recorded on ground surface during operation, both at the LEP access points and at some reference areas in the French and Swiss countryside.

  18. Positron sources for electron-positron colliders application to the ILC and CLIC

    CERN Document Server

    CERN. Geneva

    2008-01-01

    The increased demanding qualities for positron sources dedicated to e+e- colliders pushed on investigations oriented on new kinds of e+ sources. The different kinds of positron sources polarized and no polarized are considered. Their main features (intensity, emittance) are described and analysed. Comparison between the different sources is worked out. The characteristics of the positron beam available in the collision point are greatly depending on the capture device and on the positron accelerator. Different kinds of capture systems are considered and their qualities, compared. Intense positron sources which are necessary for the colliders require intense incident beams (electrons or photons). The large number of pairs created in the targets leads to important energy deposition and so, thermal heating, which associated to temperature gradients provoke mechanical stresses often destructive. Moreover, the important Coulomb collisions, can affect the atomic structure in crystal targets and the radiation resist...

  19. Interaction region for crab waist scheme of the Future Electron-Positron Collider (CERN)

    CERN Document Server

    Bogomyagkov, A

    2015-01-01

    Design study in CERN of the accelerator that would fit 80-100 km tunnel called Future Circular Colliders (FCC) includes high-luminosity $e^+ e^−$ collider (FCC-ee) with center-of-mass energy from 90 to 350 GeV to study Higgs boson properties and perform precise measurements at the electroweak scale [1–3]. Crab waist interaction region provides collisions with luminosity higher than 2 × 10$^{36}$ cm$^{−2}$ sec$^{−1}$ at beam energy of 45 GeV. The small values of the beta functions at the interaction point and distant final focus lenses are the reasons for high nonlinear chromaticity limiting energy acceptance of the whole ring. The paper describes interaction region for crab waist collision scheme in the FCC-ee, principles of tuning the chromaticity correction section in order to provide large energy acceptance.

  20. Design and optimisation of the interaction region of an electron-positron linear collider

    International Nuclear Information System (INIS)

    Strong focalization of the beam is mandatory at the interaction point of the future linear collider in order to reach very high luminosity. In this work, the ILC (International Linear Collider) beam delivery system has been re-optimised, first to take the 'push-pull' of the two detectors into account, then to evaluate the influence of a reduction of the total length by hundred meters approximately. In the following part, the interaction region has been optimised to restore the nominal luminosity in the presence of the detector, containing a solenoid and a magnetic dipole. Due to the crossing angle of the beams, these elements are not coaxial and a model for the interaction region had to be developed. This model enables to track the beam in the entire beam delivery system, from the end of the linac to the interaction point. The simulation includes for the first time all the electromagnetic elements of the interaction region (crab cavity, final focusing system quadrupoles and sextupoles, solenoid, detector integrated dipole). Thanks to this model, the weak anti-solenoid could be added and optimised as the main corrector of the solenoid effects on the beam. To study the new performances of the collider after full compensation of these effects, a luminosity calculation tool has been developed. It is shown that the momentum acceptance is reduced after compensation of the solenoid effects. Moreover, transverse coupling induces the transfer of the crab cavity horizontal kick to the vertical plane, implying a significant luminosity loss. Finally the last part of the thesis concerns the application of a large Piwinski's angle to the linear colliders. The calculation of the beam-beam interaction parameters in the presence of a crossing angle is studied. Due to the crossing angle the central trajectory is deviated in the horizontal plane, preventing the Beamstrahlung to be reduced at constant luminosity. However the disruption could be made significantly smaller. (author)

  1. Charged-particle identification with a RICH counter at an asymmetric electron-positron collider

    International Nuclear Information System (INIS)

    A high-luminosity colliding machine that operates at cms energies around 10 GeV to produce large numbers of B-mesons is now widely accepted as being one of the most important future tools for studies of the Kobayashi-Maskawa (KM) matrix elements and for understanding of the CP violation. For various reasons (e.g., time evolution of B decays, separation of B- and D-meson vertices) an asymmetric collider with a boost of the center-of-mass system around βγ = 1 seems to be the best solution. The identification of particles that covers most of the kinematically available phase space plays an essential role in the considered experimental studies at such colliders. Electron-hadron separation as well as muon identification can be well covered by other components of the spectrometer (calorimeter, differential energy-loss measurement in the tracking chamber, muon chambers in the return yoke). This paper is dedicated to the remaining hadron-hadron separation for the following reason. With standard techniques (time-of-flight measurement and the determination of energy loss in the drift chamber gas) the pion-kaon separation extends only up to momenta around 1 GeV/c5, while momenta of B-meson decay-cascade products extend to around 2.5 GeV/c with βγ = 1. A promising new technique for colliders with a high event rate is the identification with a fast ring imaging Cerenkov counter (RICH). In a RICH counter the velocity of particles is determined by measuring the Cerenkov angle (θc) for individual photons. The angle, in turn, is determined by measuring the coordinate of the photon absorption with respect to the track

  2. Isochronous storage rings and high-luminosity electron-positron colliders

    International Nuclear Information System (INIS)

    The interest in studying CP and possibly CPT violations in B- and φ-meson decay has led recently to several proposals for the construction of B- and φ-factories, with luminosity in the range of 1033 cm-2s-1 to 1034 cm-2s-1. With a conventional storage-ring collider, this high luminosity, 10 to 100 times larger than the maximum obtained up to now, is obtained by increasing the stored electron and positron beam currents from the 100-100 mA range to the several-ampere level. This very large beam current raises questions of collective instabilities, and vacuum and RF system design. In addition, the RF power needed to compensate the synchrotron radiation losses is of the order of 5 to 10 MW. In this paper, the authors propose to use an isochronous storage ring, having the particle revolution frequency independent of energy, to achieve a high luminosity with a small beam current. Isochronous rings have been discussed before as possible damping rings for linear colliders and for free electron lasers, and some of their properties have already been discussed. In this paper, the authors make a more detailed study of the beam dynamics in such a ring. The advantage of an isochronous ring are the possibility of reducing the bunch length from the present centimeter range to the millimeter range; the elimination of one class of resonances, the synchrobetatron resonances, limiting the beam density at the collision point and the interaction region geometry. The authors discuss the basic concept and some of the main properties of an isochronous ring. This discussion will define the conditions for a stable operation of an isochronous ring. The authors then consider the possibility of using an isochronous ring as a collider, along with its advantages and disadvantages. As an example, the authors will then give the main parameters of a B-factory based on this idea

  3. First year of Mark-J: physics with high energy electron-positron colliding beams. Report No. 107

    International Nuclear Information System (INIS)

    This report reviews the experimental investigation of high energy e+e- interactions by the MARK J collaboration at PETRA, the electron-positron colliding beam accelerator at DESY in Hamburg, West Germany. The physics objectives include studies of several purely electromagnetic processes and hadronic final states, which further our knowledge of the nature of the fundamental constituents and of their strong, electromagnetic and weak interactions. Before discussing the physics results, the main features and the principal components of the MARK J detector are discussed in terms of design, function, and performance. Several aspects of the online data collection and the offline analysis are also outlined. Results are presented on tests of quantum electrodynamics using e+e- → e+e-, μ+μ- and tau+tau-, on the measurement of R, the ratio of the hadronic to the point-like muon pair cross section, on the search for new quark flavors, on the discovery of three jet events arising from the radiation of hard noncollinear gluons as predicted by quantum chromodynamics, and on the determination of the strong coupling constant α/sub s/

  4. First year of Mark-J: physics with high energy electron-positron colliding beams. Report No. 107

    Energy Technology Data Exchange (ETDEWEB)

    Aachen DESY M.I.T. NIKHEF Peking Collaboration

    1980-04-01

    This report reviews the experimental investigation of high energy e/sup +/e/sup -/ interactions by the MARK J collaboration at PETRA, the electron-positron colliding beam accelerator at DESY in Hamburg, West Germany. The physics objectives include studies of several purely electromagnetic processes and hadronic final states, which further our knowledge of the nature of the fundamental constituents and of their strong, electromagnetic and weak interactions. Before discussing the physics results, the main features and the principal components of the MARK J detector are discussed in terms of design, function, and performance. Several aspects of the online data collection and the offline analysis are also outlined. Results are presented on tests of quantum electrodynamics using e/sup +/e/sup -/ ..-->.. e/sup +/e/sup -/, ..mu../sup +/..mu../sup -/ and tau/sup +/tau/sup -/, on the measurement of R, the ratio of the hadronic to the point-like muon pair cross section, on the search for new quark flavors, on the discovery of three jet events arising from the radiation of hard noncollinear gluons as predicted by quantum chromodynamics, and on the determination of the strong coupling constant ..cap alpha../sub s/.

  5. Couplers - absorbers of higher wave types for superconducting accelerating sections of linear electron-positron collider

    International Nuclear Information System (INIS)

    One studied rectangular waveguide base devices designed for removing and absorption of the wave higher types (WHT) from the superstructure of Tesla linear electron and positron collider. These devices called couplers are located between the superstructure subresonators and on its end points. WHT-couplers connected to flying tubes via the slots oriented along the tube axis (longitudinal slots), perpendicular to their axis (azimuth slots) and at a certain angle were studied. Two rectangular waveguides were used for damping of WHT of both polarities for every coupler. Paper presents the results of calculations and of experimental investigation into two copper subresonators of the superstructure. The investigations were carried out using models at room temperature and under 3 GHz frequency

  6. Probing the Top Quark Flavour-Changing Neutral Current at a Future Electron-Positron Collider

    International Nuclear Information System (INIS)

    We present a study to examine the sensitivity of a future e-e+ collider to the anomalous top flavour-changing neutral current (FCNC) to the gluon. To separate signal from background a multivariate analysis is performed on top quark pair and background events, where one top quark is considered to follow the dominant standard model (SM) decay, t→Wb, and the other top decays through FCNC, t→qg, where q is a u- or a c-quark. The analysis of fully hadronic FCNC decay of the tt- pair is also presented. The 95% confidence level limits on the top quark anomalous couplings are obtained for different values of the center-of-mass energies and integrated luminosities

  7. The production of neutral vector mesons by bremsstrahlung in electron-positron colliding beams

    International Nuclear Information System (INIS)

    The authors study the bremsstrahlung production of the rho meson in the reaction e+e- → e+e-rho (→ e+e- π+π-). This reaction gives a C = -1 background which complicates the study of C = +1 two-photon processes at the new colliding-beam facilities. The cross section for the reaction rises from approximately 0.3 nb to 0.7 nb as the beam energy increases from 2 GeV to 15 GeV. From a study of the distributions of the final leptons and pions, one finds a suitable choice of cuts which will reduce the event rate down to a small fraction of R. It is not possible to attribute the three-prong events seen at DELCO and PLUTO to this particular production mechanism. (Auth.)

  8. A system of beam energy measurement based on the Compton backscattered laser photons for the VEPP-2000 electron-positron collider

    CERN Document Server

    Abakumova, E V; Berkaev, D E; Kaminsky, V V; Koop, I A; Korol, A A; Koshuba, S V; Krasnov, A A; Muchnoi, N Yu; Perevedentsev, E A; Pyata, E E; Shatunov, P Yu; Shatunov, Yu M; Shwartz, D B

    2013-01-01

    The beam energy measurement system for the VEPP-2000 electron-positron collider is described. The method of Compton backscattering of $CO$ laser photons on the electron beam is used. The relative systematic uncertainty of the beam energy determination is estimated as 6\\cdot10^{-5}. It was obtained through comparison of the results of the beam energy measurements using the Compton backscattering and resonance depolarization methods.

  9. A system of beam energy measurement based on the Compton backscattered laser photons for the VEPP-2000 electron-positron collider

    Science.gov (United States)

    Abakumova, E. V.; Achasov, M. N.; Berkaev, D. E.; Kaminsky, V. V.; Koop, I. A.; Korol, A. A.; Koshuba, S. V.; Krasnov, A. A.; Muchnoi, N. Yu.; Perevedentsev, E. A.; Pyata, E. E.; Shatunov, P. Yu.; Shatunov, Yu. M.; Shwartz, D. B.

    2014-04-01

    The beam energy measurement system for the VEPP-2000 electron-positron collider is described. The method of Compton backscattering of CO laser photons on the electron beam is used. The relative systematic uncertainty of the beam energy determination is estimated as 6×10-5. It was obtained through comparison of the results of the beam energy measurements using the Compton backscattering and resonance depolarization methods.

  10. About the creation of proton-antiproton pair at electron-positron collider in the energy range of ψ(3770) mass

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadov, A.I., E-mail: ahmadov@theor.jinr.ru [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation); Institute of Physics, Azerbaijan National Academy of Science, Baku (Azerbaijan); Bystritskiy, Yu.M., E-mail: bystr@theor.jinr.ru [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation); Kuraev, E.A. [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation); Wang, P., E-mail: wangp@ihep.ac.cn [Institute of High Energy Physic, Chinese Academy of Science (China)

    2014-11-15

    The process of electron-positron annihilation into proton-antiproton pair is considered within the vicinity of ψ(3770) resonance. The interference between the pure electromagnetic intermediate state and the ψ(3770) state is evaluated. It is shown that this interference is destructive and the relative phase between these two contributions is large (ϕ{sub 0}≈250°)

  11. Spin correlations in nonperturbative electron-positron pair creation by petawatt laser pulses colliding with a TeV proton beam

    OpenAIRE

    T. Müller; C. Müller

    2011-01-01

    The influence of the electron spin degree of freedom on nonperturbative electron-positron pair production by high-energy proton impact on an intense laser field of circular polarization is analyzed. Predictions from the Dirac and Klein-Gordon theories are compared and a spin-resolved calculation is performed. We show that the various spin configurations possess very different production probabilities and discuss the transfer of helicity in this highly nonlinear process. Our predictions could ...

  12. Electron-positron interactions

    International Nuclear Information System (INIS)

    The experimental information available on e+e- interactions at the time of the Tbilisi Conference (Juli 1976) is reviewed. The topics of these lectures are: electron-positron storage rings, purely electromagnetic ee-interactions, phenomenology of hadron production, e+e- annihilation at low energies, nonresonant hadron production, the new particles psi-3105 and psi-3695, research for other vector states, radiative decays of psi-3105 and psi-3695, anti Q-Q model and predictions, the bound states of heavy quarks, data on new states with even charge conjugation, mesons with open charm, experimental evidence for charmed mesons and for a new lepton. (BJ)

  13. Experiments on electron-electron, positron-electron and proton-proton colliding beams in the SAN SSSR Insitute for Nuclear Physics

    International Nuclear Information System (INIS)

    Results of development of a VEP-1 and VEPP-2 electron-electron, electron-positron and proton-proton storage rings and an air-core proton synchrotron are given. The VEP-1 comprises a B-2S heavy-current electron synchrotron, a coupled system of two high-vacuum magnetic tracks, and electron-optical channel for beam transport from the accelerator on the tracks and a single-turn output-input system. The VEPP-2 comprises a B-3M heavy-current electron synchrotron, high-vacuum magnetic track, a converter to convert an electron beam to a positron one, an electron-optical system for the beam transport and a system of single-turn beam extraction from the accelerator and input into the accumulation track. The air-core proton synchrotron with weak focusing and a balanced central busbar has the radius of the equilibrium orbit being equal to 2 m, h magnetic field - approximately to 200 kGs. First results on beam storage are given

  14. Investigation of the process e+e− → K+K− with the aid of the CMD-3 detector at the VEPP-2000 electron-positron collider

    International Nuclear Information System (INIS)

    Preliminary results of an experiment that is aimed at measuring the cross section for the process e+e− → K+K− at c.m. energies in the range between 1.01 and 2.0 GeV with the aid of the CMD-3 detector and which is being performed at the VEPP-2000 collider of the Budker Institute of Nuclear Physics (Novosibirsk, Siberian Branch, Russian Academy of Sciences) are presented

  15. Ultrarelativistic Electron-Positron Plasma

    CERN Document Server

    Thoma, Markus H

    2008-01-01

    Ultrarelativistic electron-positron plasmas can be produced in high-intensity laser fields and play a role in various astrophysical situations. Their properties can be calculated using QED at finite temperature. Here we will use perturbative QED at finite temperature for calculating various important properties, such as the equation of state, dispersion relations of collective plasma modes of photons and electrons, Debye screening, damping rates, mean free paths, collision times, transport coefficients, and particle production rates, of ultrarelativistic electron-positron plasmas. In particular, we will focus on electron-positron plasmas produced with ultra-strong lasers.

  16. Future Prospects at Electron-Positron Machines

    CERN Document Server

    Roney, J Michael

    2013-01-01

    This review will present the future prospects for physics at electron-positron colliders running near the Upsilon(4S) as well as at the charm and tau thresholds. It includes a review of the Belle II and SuperB projects. Also reviewed are the plans for BES III, which operates near the charm threshold at the IHEP BEPC machine in Bejing and the status of the Super Charm/Tau Factory proposed for the Budker Institute for Nuclear Physics (BINP) in Novosibirsk.

  17. Electron positron factories

    International Nuclear Information System (INIS)

    In this paper, we will first indicate the key issues in designing a B-factory and a φ-factory, and illustrate the approaches that are being followed to address them. In general, reaching the B-factory parameter regime offers the most challenges, so we will emphasize it here. Then we will consider an extrapolation of our present understanding of collider performance and assess the maximum luminosity that could be anticipated. To reach extremely high luminosity, it may be necessary to consider possibilities beyond the scope of ''standard'' approaches to collider design; a few illustrative examples are outlined. For both the present designs and the extrapolated parameters, R ampersand D activities in a few key areas are required; these areas are discussed in this paper also

  18. Resummed jet rates with heavy quarks in electron-positron collisions

    OpenAIRE

    Rodrigo, German; Krauss, Frank

    2003-01-01

    Expressions for Sudakov form factors for heavy quarks are presented. They are used to construct resummed jet rates in electron-positron annihilation. Predictions are given for production of bottom quarks at LEP and top quarks at the Linear Collider.

  19. A mega watt electron positron conversion target

    International Nuclear Information System (INIS)

    Intense sources of positrons are required to achieve in high energy electron-positron colliders the desired elevated luminosities. Positrons are produced by diverting part of the high energy electrons onto a target, from which low energy positrons are collected and re-injected into the e--e+ collider. Within the frame of a design study for a high luminosity beauty factory, ARES [1] presently under consideration at FRASCATI, a conceptual design has been worked out for the targeting of a 2 GeV- electron beam with an average current of 770 μA and an average power of 1.5 MW. In order to handle these extreme power densities, a rotating wheel is considered intercepting the beam at its periphery such that the beam power is spread around its circumference. The target concept has already been described earlier. In this paper the authors summarize the principle features, consider certain critical technical aspects and discusses in some detail the prevailing radiation problems

  20. The PEP electron-positron ring

    International Nuclear Information System (INIS)

    The first stage of the positron-electron-proton (PEP) colliding-beam system which has been under joint study by a Lawrence Berkeley Laboratory-Stanford Linear Accelerator Center team for the past two years, will be the electron-positron storage ring. The physics justification for the e+e/sup minus/ ring is summarized briefly and the proposed facility is described. The ring will have six arcs having gross radii of about 220 m and six interaction regions located at the centers of straight sections about 130 m long. The longitudinal distance left free for experimental apparatus at the intersection regions will be 20 m. The range of operating beam energies will be from 5 GeV to 15 GeV. The design luminosity at 15 GeV will be 1032cm/sup minus 2/s/sup minus 1/, and the luminosity will vary approximately as the square of the beam energy. Alternative methods under consideration for adjusting the beam cross-section are discussed. The designs of the storage ring subsystems and of the conventional facilities including the experimental halls at the interaction regions are described

  1. Study of electron-positron interactions

    International Nuclear Information System (INIS)

    For the past seven years, this group has been interested in the study of tests of the Standard Model of Electroweak interactions. The program has centered about the AMY experiment which examines the nature of the final state products in electron-positron collisions in the center of mass energy range near 60 GeV. Results of these measurements have shown a remarkable consistency with the predictions of the minimal model of 3 quark and lepton generations and single charged and neutral intermediate bosons. No new particles or excited states have been observed nor has any evidence for departures in cross sections or angular asymmetries from expectations been observed. These conclusions have been even more firmly established by the higher energy results from the LEP and SLC colliders at center of mass energies of about 90 GeV. Our focus is shifting to the neutrino as a probe to electroweak interactions. The relative merit of attempting to observe neutrinos from point sources versus observing neutrinos generally is not easy to predict. The improved ability to interpret is offset by the probably episodic nature of the emission and irreproducibility of the results. In this phase of development, it is best to be sensitive to both sources of neutrinos. As a second phase of our program at Virginia Tech, we are studying the feasibility of detecting cosmic ray neutrinos in a proposed experiment which we have called NOVA. the results of the test setup will be instrumental in developing an optimum design. A third program we are involved in is the MEGA experiment at Los Alamos, an experiment to place a limit on the rate of muon decay to electron plus photon which is forbidden by the Standard Model

  2. Beijing

    Institute of Scientific and Technical Information of China (English)

    WANGPEI

    2004-01-01

    As the nation's capital, Beijing hasunderstandably been positioned as China's political and cultural centel As the second largest economy among China's cities according to figures for 2003, Beijing also earns the title of an economic center. In the past two years Beijing has started to realize the indispensable value of finance for its overall economic development and set out to build a financial area in the city.

  3. Physicists dream of supersized collider

    Science.gov (United States)

    Hao, Cindy

    2015-12-01

    Particle physicists in China are hopeful that the Chinese government will allocate 1 billion yuan (about £104m) to design what would be the world's largest particle accelerator - the Circular Electron Positron Collider (CEPC).

  4. The Dismantling Project for the Large Electron Positron (LEP) Collider

    CERN Document Server

    Poole, John

    2002-01-01

    The LEP accelerator was installed in a circular tunnel 27 km in length with nine access points distributed around the circumference in the countryside and villages which surround CERN's sites. The dismantling project involved the removal in less than 15 months of around 29000 tonnes of equipment from the accelerator itself and a further 10000 tonnes from the four experiments - all of which were located at an average depth of 100 m below ground level. There was no contamination risk in the project and less than 3% of the materials removed were classified as radioactive. However, the materials which were classified as radioactive have to be temporarily stored and they consume considerable resources. The major difficulties for the project were in the establishment of the theoretical radiological zoning, implementation of the traceability systems and making appropriate radiation measurements to confirm the zoning. The absence of detailed guidelines from the French authorities, having no threshold levels for relea...

  5. Timelike Virtual Compton Scattering from Electron-Positron Radiative Annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Afanasev, Andrei; /Hampton U. /Jefferson Lab; Brodsky, Stanley J.; /SLAC; Carlson, Carl E.; /William-Mary Coll.; Mukherjee, Asmita; /Indian Inst. Tech., Mumbai

    2009-03-31

    We propose measurements of the deeply virtual Compton amplitude (DVCS) {gamma}* {yields} H{bar H}{gamma} in the timelike t = (p{sub H} + p{sub {bar H}}){sup 2} > 0 kinematic domain which is accessible at electron-positron colliders via the radiative annihilation process e{sup +}e{sup -} {yields} H{bar H}{gamma}. These processes allow the measurement of timelike deeply virtual Compton scattering for a variety of H{bar H} hadron pairs such as {pi}{sup +}{pi}{sup -}, K{sup +}K{sup -}, and D{bar D} as well as p{bar p}. As in the conventional spacelike DVCS, there are interfering coherent amplitudes contributing to the timelike processes involving C = - form factors. The interference between the amplitudes measures the phase of the C = + timelike DVCS amplitude relative to the phase of the timelike form factors and can be isolated by considering the forward-backward e{sup +} {leftrightarrow} e{sup -} asymmetry. The J = 0 fixed pole contribution which arises from the local coupling of the two photons to the quark current plays a special role. As an example we present a simple model.

  6. Timelike Virtual Compton Scattering from Electron-Positron Radiative Annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Andrei Afanaciev,Andrei Afanasev, Stanley J. Brodsky, Carl E. Carlson, Asmita Mukherjee

    2010-02-01

    We propose measurements of the deeply virtual Compton amplitude (DVCS), gamma* to H H-bar gamma, in the timelike t = (p_{H} + p_{H-bar})^2 > 0 kinematic domain which is accessible at electron-positron colliders via the radiative annihilation process e+ e- to H H-bar gamma. These processes allow the measurement of timelike deeply virtual Compton scattering for a variety of H H-bar hadron pairs such as pi+ pi-, K+ K-, and D D-bar as well as p p-bar. As in the conventional spacelike DVCS, there are interfering coherent amplitudes contributing to the timelike processes involving C= - form factors. The interference between the amplitudes measures the phase of the C=+ timelike DVCS amplitude relative to the phase of the timelike form factors and can be isolated by considering the forward-backward e+ \\leftrightarrow e- asymmetry. The J=0 fixed pole contribution which arises from the local coupling of the two photons to the quark current plays a special role. As an example we present a simple model.

  7. Electron-positron high efficiency converter

    International Nuclear Information System (INIS)

    This work is concerned with new possible hardware to produce positrons in the upgraded CESR (Cornell University, USA) linac injector by the enhanced power capacity of the converter and improved focusing of the emerging positrons. The paper describes the design of the converter which can handle 200 MeV incident beams carrying 6 kW average power. In this work it is suggested to design the quarter wave transformer (QWT) from two Helmholtz coils. The electron-positron converter is placed in the median plane of the QWT which is located in the middle of the flat top of the magnetic field Bi (z) distribution. In addition it is suggested to increase Bi up to a level of ∼2.5 T and a solenoidal magnetic field Bf extending over the first e+-linac section up to the level of ∼0.5 T. Calculations have shown that the conversion efficiency about 1% can be achieved for an electron beam having r.m.s. diameter σr∼3 mm. An additional factor of about 2 may be obtained by decreasing σr to 1.5 mm. 15 refs., 6 figs., 4 tabs

  8. FCC based ep and \\mu p colliders

    CERN Document Server

    Acar, Y C; Oner, B B; Sultansoy, S

    2015-01-01

    Construction of future electron-positron colliders (or dedicated electron linac) and muon colliders close to Future Circular Collider will give opportunity to utilize highest energy proton and nucleus beams for lepton-hadron and photon-hadron collisions. In this paper we estimate main parameters of the FCC based ep and \\mu p colliders.

  9. Colliders

    CERN Document Server

    Chou, Weiren

    2014-01-01

    The idea of colliding two particle beams to fully exploit the energy of accelerated particles was first proposed by Rolf Wideröe, who in 1943 applied for a patent on the collider concept and was awarded the patent in 1953. The first three colliders — AdA in Italy, CBX in the US, and VEP-1 in the then Soviet Union — came to operation about 50 years ago in the mid-1960s. A number of other colliders followed. Over the past decades, colliders defined the energy frontier in particle physics. Different types of colliers — proton–proton, proton–antiproton, electron–positron, electron–proton, electron-ion and ion-ion colliders — have played complementary roles in fully mapping out the constituents and forces in the Standard Model (SM). We are now at a point where all predicted SM constituents of matter and forces have been found, and all the latest ones were found at colliders. Colliders also play a critical role in advancing beam physics, accelerator research and technology development. It is timel...

  10. Physics at Future Colliders

    OpenAIRE

    Ellis, John

    1997-01-01

    After a brief review of the Big Issues in particle physics, we discuss the contributions to resolving that could be made by various planned and proposed future colliders. These include future runs of LEP and the Fermilab Tevatron collider, B factories, RHIC, the LHC, a linear electron-positron collider, an electron-proton collider in the LEP/LHC tunnel, a muon collider and a future larger hadron collider (FLHC). The Higgs boson and supersymmetry are used as benchmarks for assessing their capa...

  11. Bound-free electron-positron pair production in relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    The bound-free electron-positron pair production is considered for relativistic heavy ion collisions. In particular, cross sections are calculated for the pair production with the simultaneous capture of the electron into the 1s ground state of one of the ions and for energies that are relevant for the relativistic heavy ion collider and the large hadron colliders. In the framework of perturbation theory, we applied Monte Carlo integration techniques to compute the lowest-order Feynman diagrams amplitudes by using Darwin wave functions for the bound states of the electrons and Sommerfeld-Maue wave functions for the continuum states of the positrons. Calculations were performed especially for the collision of Au+Au at 100 GeV/nucleon and Pb+Pb at 3400 GeV/nucleon.

  12. Performance study of the Beijing intense slow positron beam

    International Nuclear Information System (INIS)

    A slow positron beam based on the Beijing Electron-Positron Collider (BEPC) has been constructed and tested. In this paper, transmission efficiency and other performance parameters of the system are measured by a series of experiments on the pulsed slow positron beam. Results show that the transmission efficiency of the transfer system is above 98% and the size of pulsed slow positron beam's image got by the IP is less than 15 mm. At the same time, the energy spread of the pulsed slow positron beam is about 10 eV (FWHM). The pulsed beam intensity is about 106 slow positrons/s when BEPC is running under the short-pulse mode. It is also shown that the intensity would be reduced to half of initial value after storing 40 ms at 3 x 10-7 Pa vacuum level. (authors)

  13. Solitary waves in asymmetric electron-positron-ion plasmas

    Science.gov (United States)

    Lu, Ding; Li, Zi-Liang; Xie, Bai-Song

    2015-10-01

    > By solving the coupled equations of the electromagnetic field and electrostatic potential, we investigate solitary waves in an asymmetric electron-positron plasma and/or electron-positron-ion plasmas with delicate features. It is found that the solutions of the coupled equations can capture multipeak structures of solitary waves in the case of cold plasma, which are left out by using the long-wavelength approximation. By considering the effect of ion motion with respect to non-relativistic and ultra-relativistic temperature plasmas, we find that the ions' mobility can lead to larger-amplitude solitary waves; especially, this becomes more obvious for a high-temperature plasma. The effects of asymmetric temperature between electrons and positrons and the ion fraction on the solitary waves are also studied and presented. It is shown that the amplitudes of solitary waves decrease with positron temperature in asymmetric temperature electron-positron plasmas and decrease also with ion concentration.

  14. The Angular Distribution Of Electron-positron Pairs From Exclusive Charmonium Decays In Antiproton-proton Annihilations

    CERN Document Server

    McTaggart, R J

    1998-01-01

    The angular distributions of the charmonium resonances J/ Y (3097) and Y (3686) in their exclusive decay to an electron-positron pair are studied. Experiment 835 at the Fermi National Accelerator Laboratory produced charmonium resonances by annihilating protons with antiprotons in the Fixed Target Mode of the Antiproton Accumulator: A stochastically cooled antiproton beam collides with a hydrogen gas jet, which forms clusters under the right pressure and low temperature. The charmonium decay products are detected out of a large hadronic background with the help of a segmented lead glass sampling calorimeter, which is sensitive to the high mass electron-positron charmonium decay, and a set of Cerenkov threshold detectors that provide good electron/pion separation. Several factors influence the angular distribution parameter l taken from the angular distribution, including the energy scale of the resonance, the coupling strength of the charmonium atom, and how quarks and gluons interact in the dissolution...

  15. Enhanced subthreshold electron-positron production in short laser pulses

    OpenAIRE

    Titov, A. I.; Takabe, H.; Kampfer, B.; Hosaka, A.

    2012-01-01

    The emission of electron-positron pairs off a probe photon propagating through a polarized short-pulsed electromagnetic (e.g.\\ laser) wave field is analyzed. A significant increase of the total cross section of pair production in the subthreshold region is found for decreasing laser pulse duration even in case of moderate laser pulse intensities.

  16. Extracting the Size of the Cosmic Electron-Positron Anomaly

    Science.gov (United States)

    Auchettl, Katie; Balazs, C.

    2011-09-01

    Over the last few decades, numerous observations have hinted at an excess of high energy positrons in our locality. The most recent of these experiments has been the positron fraction measured by the PAMELA satellite and the electron plus positron spectrum as measured by the Fermi-LAT satellite. Since the release of these measurements, there have been a plethora of papers where authors invoke new physics ranging from, modification of the cosmic ray propagation, supernova remnants and dark matter annihilation. Using a Bayesian likelihood analysis, we isolate the anomalous contribution of the cosmic electron-positron flux. A significant tension was found between the electron positron related data and non-electron-positron cosmic ray fluxes. Using 219 recent cosmic ray datum, we extracted the preferred values of the selected cosmic ray propagation parameters from the non-electron-positron related measurements. Based on these parameter values we calculated background predictions with uncertainties for PAMELA and Fermi-LAT. We found a deviation between the PAMELA and Fermi-LAT data and the predicted background even when uncertainties, including systematics, were taken into account. Interpreting this as a hint of new physics, we subtracted the background from the data extracting the size, shape and uncertainty of the anomalous contribution in a model independent fashion. We briefly compared the extracted signal to some theoretical results predicting such an anomaly.

  17. Production of new particles in electron-positron annihilation

    International Nuclear Information System (INIS)

    A number of areas are reviewed where there is important progress in the production of new particles in electron--positron annihilation, but of a more detailed quantitative nature. Charmonium states, charmed mesons, and evidence for a charged heavy lepton are covered. 50 references

  18. TESLA*HERA Based gamma-p and gamma-A Colliders

    OpenAIRE

    Ciftci, A. K.; Sultansoy, S.; Yavas, O.

    2000-01-01

    Main parameters and physics search potential of gamma-p and gamma-A colliders, which will be available due to constructing the TESLA linear electron-positron collider tangentially to the HERA proton ring, are discussed.

  19. Measurement of the hadronic cross section in electron-positron annihilation

    International Nuclear Information System (INIS)

    This thesis describes the most precise measurement to date of the ratio R, the hadronic cross section in lowest order electron-positron annihilation to the cross section for muon pair production in lowest order electron-positron annihilation. This experiment is of interest because R is a fundamental parameter that tests in a model independent way the basic assumptions of strong interaction theories. According to the assumptions of one of these theories the value of R is determined simply from the electric charges, spin, and color assignments of the produced quark-pairs. The experiment was carried out with the MAgnetic Calorimeter using collisions of 14.5 GeV electrons and positrons at the 2200m circumference PEP storage ring at SLAC. The MAC detector is one of the best-suited collider detectors for measuring R due to its nearly complete coverage of the full angular range. The data for this experiment were accumulated between February 1982 and April 1983 corresponding to a total event sample of about 40,000 hadronic events. About 5% of the data were taken with 14 GeV beams and the rest of the data were taken with 14.5 GeV beams. A description of particle interactions and experimental considerations is given

  20. Electroweak Measurements in Electron-Positron Collisions at W-Boson-Pair Energies at LEP

    CERN Document Server

    Schael, S; Bruneliere, R; Buskulic, D; De Bonis, I; Decamp, D; Ghez, P; Goy, C; Jezequel, S; Lees, J P; Lucotte, A; Martin, F; Merle, E; Minard, M N; Nief, J Y; Odier, P; Pietrzyk, B; Trocme, B; Bravo, S; Casado, M P; Chmeissani, M; Comas, P; Crespo, J M; Fernandez, E; Fernandez-Bosman, M; Garrido, Ll; Grauges, E; Juste, A; Martinez, M; Merino, G; Miquel, R; Mir, Ll. M; Orteu, S; Pacheco, A; Park, I C; Perlas, J; Riu, I; Ruiz, H; Sanchez, F; Colaleo, A; Creanza, D; De Filippis, N; De Palma, M; Iaselli, G; Maggi, G; Maggi, M; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Bazarko, A; Becker, U; Boix, G; Bird, F; Blucher, E; Bonvicini, B; Bright-Thomas, P; Barklow, T; Buchmuller, O; Cattaneo, M; Cerutti, F; Ciulli, V; Clerbaux, B; Drevermann, H; Forty, R W; Frank, M; Greening, T C; Hagelberg, R; Halley, A W; Gianotti, F; Girone, M; Hansen, J B; Harvey, J; Jacobsen, R; Hutchcroft, D E; Janot, P; Jost, B; Knobloch, J; Kado, M; Lehraus, I; Lazeyras, P; Maley, P; Mato, P; May, J; Moutoussi, A; Pepe-Altarelli, M; Ranjard, F; Rolandi, L; Schlatter, D; Schmitt, B; Schneider, O; Tejessy, W; Teubert, F; Tomalin, I R; Tournefier, E; Veenhof, R; Valassi, A; Wiedenmann, W; Wright, A E; Ajaltouni, Z; Badaud, F; Chazelle, G; Deschamps, O; Dessagne, S; Falvard, A; Ferdi, C; Fayolle, D; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Pascolo, J M; Perret, P; Podlyski, F; Bertelsen, H; Fernley, T; Hansen, J D; Hansen, J R; Hansen, P H; Kraan, A C; Lindahl, A; Mollerud, R; Nilsson, B S; Rensch, B; Waananen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, E; Siotis, I; Vayaki, A; Zachariadou, K; Blondel, A; Bonneaud, G; Brient, J C; Machefert, F; Rouge, A; Rumpf, M; Swynghedauw, M; Tanaka, R; Verderi, M; Videau, H; Ciulli, V; Focardi, E; Parrini, G; Zachariadou, K; Corden, M; Georgiopoulos, C; Antonelli, A; Antonelli, M; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Cerutti, F; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, G P; Passalacqua, L; Picchi, P; Colrain, P; Have, I. ten; Hughes, I S; Kennedy, J; Knowles, I G; Lynch, J G; Morton, W T; Negus, P; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Thompson, A S; Turnbull, R M; Wasserbaech, S; Buchmuller, O; Cavanaugh, R; Dhamotharan, S; Geweniger, C; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Sommer, J; Stenzel, H; Tittel, K; Werner, W; Wunsch, M; Beuselinck, R; Binnie, D M; Cameron, W; Davies, G; Dornan, P J; Goodsir, S; Marinelli, N; Martin, E B; Nash, J; Nowell, J; Rutherford, S A; Sedgbeer, J K; Thompson, J C; White, R; Williams, M D; Ghete, V M; Girtler, P; Kneringer, E; Kuhn, D; Rudolph, G; Bouhova-Thacker, E; Bowdery, C K; Buck, P G; Clarke, D P; Ellis, G; Finch, A J; Foster, F; Hughes, G; Jones, R.W L; Keemer, N R; Pearson, M R; Robertson, N A; Sloan, T; Smizanska, M; Snow, S W; Williams, M I; van der Aa, O; Delaere, C; Leibenguth, G; Lemaitre, V; Bauerdick, L.A T; Blumenschein, U; van Gemmeren, P; Giehl, I; Holldorfer, F; Jakobs, K; Kasemann, M; Kayser, F; Kleinknecht, K; Muller, A S; Quast, G; Renk, B; Rohne, E; Sander, H G; Schmeling, S; Wachsmuth, H; Wanke, R; Zeitnitz, C; Ziegler, T; Aubert, J J; Benchouk, C; Bonissent, A; Carr, J; Coyle, P; Curtil, C; Ealet, A; Etienne, F; Fouchez, D; Motsch, F; Payre, P; Rousseau, D; Tilquin, A; Talby, M; Thulasidas, M; Aleppo, M; Antonelli, M; Ragusa, F; Buscher, V; David, A; Dietl, H; Ganis, G; Huttmann, K; Lutjens, G; Mannert, C; Manner, W; Moser, H G; Settles, R; Seywerd, H; Stenzel, H; Villegas, M; Wiedenmann, W; Wolf, G; Azzurri, P; Boucrot, J; Callot, O; Chen, S; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, Ph; Jacholkowska, A; Le Diberder, F; Lefrancois, J; Mutz, A M; Schune, M H; Serin, L; Veillet, J J; Videau, I; Zerwas, D; Azzurri, P; Bagliesi, G; Bettarini, S; Boccali, T; Bozzi, C; Calderini, G; Dell'Orso, R; Fantechi, R; Ferrante, I; Fidecaro, F; Foa, L; Giammanco, A; Giassi, A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, F; Rizzo, G; Sanguinetti, G; Sciaba, A; Sguazzoni, G; Spagnolo, P; Steinberger, J; Tenchini, R; Vannini, C; Venturi, A; Verdini, P G; Awunor, O; Blair, G A; Cowan, G; Garcia-Bellido, A; Green, M G; Medcalf, T; Misiejuk, A; Strong, J A; Teixeira-Dias, P; Botterill, D R; Clifft, R W; Edgecock, T R; Edwards, M; Haywood, S J; Norton, P R; Tomalin, I R; Ward, J J; Bloch-Devaux, B; Boumediene, D; Colas, P; Emery, S; Fabbro, B; Kozanecki, W; Lancon, E; Lemaire, M C; Locci, E; Perez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Tuchming, B; Vallage, B; Black, S N; Dann, J H; Kim, H Y; Konstantinidis, N; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Cartwright, S

    2013-01-01

    Electroweak measurements performed with data taken at the electron-positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3~fb$^{-1}$ collected by the four LEP experiments ALEPH, DELPHI, L3 and OPAL, at centre-of-mass energies ranging from $130~GeV$ to $209~GeV$. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron-positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose-Einstein correlations between the two W decay systems arising ...

  1. New Longitudinal Waves in Electron-Positron-Ion Quantum Plasmas

    CERN Document Server

    Tsintsadze, Nodar L; Rehman, A; Murtaza, G

    2010-01-01

    A general quantum dispersion equation for electron-positron(hole)-ion quantum plasmas is derived and studied for some interesting cases. In an electron-positron degenerate Fermi gas, with or without the Madelung term, a new type of zero sound waves are found. Whereas in an electron-hole plasmas a new longitudinal quantum waves are revealed, which have no analogies in quantum electron-ion plasmas. The excitation of these quantum waves by a low-density monoenergetic straight electron beam is examined. Furthermore, the KdV equation for novel quantum waves is derived and the contribution of the Madelung term in the formation of the KdV solitons is discussed.

  2. Electron-positron pair generation in a bichromatic laser field

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, Martin Josef Alexander; Mueller, Carsten [Institut fuer Theoretische Physik I, Heinrich-Heine-Universitaet Duesseldorf, Universitaetsstrasse 1, 40225 Duesseldorf (Germany)

    2013-07-01

    The creation of an electron-positron pair resulting from the collision of photons was first considered by Breit and Wheeler and experimentally observed at SLAC. We regard the case of a bi-chromatic laser field, where quantum inferences can be expected. In our analysis, the generated particles are described by Volkov solutions of the corresponding Klein-Gordon Equation. We discuss effects related to the relative phase of the two fields as well as interference effects between different absorption channels.

  3. Electromagnetic Solitons in Degenerate Relativistic Electron-Positron Plasma

    CERN Document Server

    Berezhiani, V I; Tsintsadze, N L

    2014-01-01

    The existence of soliton-like electromagnetic (EM) distributions in a fully degenerate electron-positron plasma is studied applying relativistic hydrodynamic and Maxwell equations. For circularly polarized wave it is found that the soliton solutions exist both in relativistic as well as nonrelativistic degenerate plasmas. Plasma density in the region of soliton pulse localization is reduced considerably. The possibility of plasma cavitation is also shown.

  4. Precision Measurements in Electron-Positron Annihilation: Theory and Experiment

    CERN Document Server

    Chetyrkin, Konstantin

    2016-01-01

    Theory results on precision measurements in electron-positron annihilation at low and high energies are collected. These cover pure QCD calculations as well as mixed electroweak and QCD results, involving light and heavy quarks. The impact of QCD corrections on the $W$-boson mass is discussed and, last not least, the status and the perspectives for the Higgs boson decay rate into $b\\bar b$, $c\\bar c$ and into two gluons.

  5. Comments on charm production in electron positron annihilation

    International Nuclear Information System (INIS)

    The circumstances are discussed in which the production of D anti D: DD*: D* anti D* in electron positron annihilation is expected to be in the ratio 1:4:7 suggested by counting the available spin states. The physical significance of the requisite assumptions is discussed. The importance of taking into account the finite detector acceptance is stressed and tests for a possible 3D1 component in the D* are proposed. (author)

  6. ''Heavy light bullets'' in electron-positron plasma

    International Nuclear Information System (INIS)

    The nonlinear propagation of circularly polarized electromagnetic waves with relativistically strong amplitudes in an unmagnetized hot electron-positron plasma with a small fraction of ions is investigated. The possibility of finding localized solutions in such a plasma is explored. It is shown that these plasmas support the propagation of ''heavy light bullets''; nondiffracting and nondispersive electromagnetic (EM) pulses with large density bunching. (author). 24 refs, 12 figs

  7. Detectors for Linear Colliders: Detector design for a Future Electron-Positron Collider (4/4)

    CERN Document Server

    CERN. Geneva

    2010-01-01

    In this lecture I will discuss the issues related to the overall design and optimization of a detector for ILC and CLIC energies. I will concentrate on the two main detector concepts which are being developed in the context of the ILC. Here there has been much recent progress in developing realistic detector models and in understanding the physics performance of the overall detector concept. In addition, I will discuss the how the differences in the detector requirements for the ILC and CLIC impact the overall detector design.

  8. Study on energy and position resolution of MWPC for the Beijing e/π test beam

    International Nuclear Information System (INIS)

    This paper describes the research on the energy and position resolution of the MWPC used in the e/π Test Beam on BEPC (Beijing Electron Positron Collider), which localizes the particles of e/π by the readout method of gravity center of the induced charges on the cathode strips. The spatial resolution of about 0.24 mm and energy resolution of 17% for 5.9 keV γ photons are attained at the 3700 V anode voltage. For the 1.1 GeV electrons, the spatial resolution of 0.3 mm is obtained. The contributions of various factors to energy resolution are analysed. It is found that energy resolution is changed with the anode voltage and there exists a least energy resolution. The reasons for these are discussed. (authors)

  9. Design of the magnetic field system for Beijing intense slow positron beam transportation

    International Nuclear Information System (INIS)

    A slow positron beam with intensity of 106 e+/s produced by the Beijing Electron-Positron Collider (BEPC) is transported by the 100 Gauss magnetic field system with the oscillation less that 10%. In this paper, the distributions of magnetic field at target chamber, sample chamber and Penning-Trap storage are calculated systematically, and the parameters of solenoidal coils and steering coils are calculated respectively. The correction coils are designed to compensate the affect induced by the geomagnetic field and the bent tube. Results of electron beam experiment show that the positron beams are transported to sample chamber with the beam spot size basically unchanged, and the magnetic field distributions satisfy to the requirement of the slow positron beam system

  10. Optical distortions in electron/positron storage rings

    International Nuclear Information System (INIS)

    We have studied the optical distortions in the PEP electron/positron storage ring for various optical configurations using the computer programs DIMAT, HARMON, PATRICIA, and TURTLE. The results are shown graphically by tracing several thousand trajectories from one interaction region to the next using TURTLE and by tracing a few selected rays several hundred turns using the programs DIMAT and PATRICIA. The results show an interesting correlation between the calculated optical cleanliness of a particular lattice configuration and the observed operating characteristics of the machine

  11. Thomson scattering off a pair (electron-positron) plasma

    Institute of Scientific and Technical Information of China (English)

    Zheng Jian

    2006-01-01

    Thomson scattering off a pair (electron-positron) plasma is theoretically investigated in the collisionless and collisional limits respectively. Our calculations show that the power spectrum of the Thomson scattering offa collisionless pair plasma is just proportional to the velocity distribution function of the particles in the plasma. Collective modes in the plasma do not have any effects on the Thomson scattering spectrum because of the correlation between the negatively- and positively-charged particles. In the collisional limit, the power spectrum of the Thomson scattering presents three spikes: two peaks correspond to two contra-propagating sound waves and one peak corresponds to an entropy wave.

  12. The Cornell electron-positron storage ring - CESR

    International Nuclear Information System (INIS)

    At the Laboratory of Nuclear Studies of Cornell University we are working on a project to convert the present 12 GeV electron synchrotron complex into the Cornell Electron-Positron Storage Ring - CESR. The design studies for this new device were begun in early 1975. During the past eighteen months the National Science Foundation has supported a program of research and development on CESR and funds to begin construction are included in the NSF budget now before the U.S. Congress. Our goal is to have CESR in operation in the fall of 1979. (orig.)

  13. Electron-positron Annihilation Lines and Decaying Sterile Neutrinos

    OpenAIRE

    Chan, M. H.; Chu, M. -C.

    2011-01-01

    If massive sterile neutrinos exist, their decays into photons and/or electron-positron pairs may give rise to observable consequences. We consider the possibility that MeV sterile neutrino decays lead to the diffuse positron annihilation line in the Milky Way center, and we thus obtain bounds on the sterile neutrino decay rate $\\Gamma_e \\ge 10^{-28}$ s$^{-1}$ from relevant astrophysical/cosmological data. Also, we expect a soft gamma flux of $1.2 \\times 10^{-4}-9.7 \\times 10^{-4}$ ph cm$^{-2}...

  14. Four-Fermion Production in Electron-Positron Collisions

    CERN Document Server

    Grünewald, M W; Accomando, E; Ballestrero, A; Bambade, P; Bardin, Dimitri Yuri; Beenakker, W; Berends, F A; Boos, E; Chapovsky, A P; Denner, A; Dittmaier, S; Dubinin, M N; Hansen, J B; Ilyin, V A; Jadach, Stanislaw; Kurihara, Y; Kuroda, M; Maina, E; Montagna, G; Moretti, M; Nicrosini, O; Olshevskii, A G; Osmo, M; Pallavicini, A; Papadopoulos, C G; Phillips, H T; Piccinini, Fulvio; Pittau, R; Placzek, Wiesiek; Riemann, Tord; Roth, M; Schmidt-Kärst, S; Shimizu, Y; Skrzypek, Maciej; Tanaka, R; Verzocchi, M; Wackeroth, D; Ward, B F L; Was, Zbigniew; Gruenewald, Martin W.; Passarino, Giampiero

    2000-01-01

    This report summarises the results of the four-fermion working group of the LEP2-MC workshop, held at CERN from 1999 to 2000. Recent developments in the calculation of four-fermion processes in electron-positron collisions at LEP-2 centre-of-mass energies are presented, concentrating on predictions for four main reactions: W-pair production, visible photons in four-fermion events, single-W production and Z-pair production. Based on a comparison of results derived within different approaches, theoretical uncertainties on these predictions are established.

  15. Gyrokinetic stability theory of electron-positron plasmas

    CERN Document Server

    Helander, Per

    2016-01-01

    The linear gyrokinetic stability properties of magnetically confined electron-positron plasmas are investigated in the parameter regime most likely to be relevant for the first laboratory experiments involving such plasmas, where the density is small enough that collisions can be ignored and the Debye length substantially exceeds the gyroradius. Although the plasma beta is very small, electromagnetic effects are retained, but magnetic compressibility can be neglected. The work of a previous publication (Helander, 2014) is thus extended to include electromagnetic instabilities, which are of importance in closed-field-line configurations, where such instabilities can occur at arbitrarily low pressure. It is found that gyrokinetic instabilities are completely absent if the magnetic field is homogeneous: any instability must involve magnetic curvature or shear. Furthermore, in dipole magnetic fields, the stability threshold for interchange modes with wavelengths exceeding the Debye radius coincides with that in i...

  16. Electron-positron pair creation in heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Mai, Manuel [Physikalisches Institut, Universitaet Heidelberg (Germany)

    2011-07-01

    A theoretical description of highly charged ion collisions is given. At collision energies near the Coulomb barrier the formation of so quasi molecules can happen, with a ground state that dives into the ''Dirac sea'' at short distances of the ions. In that way an electron-positron pair can be created. For two ions traveling on classical Rutherford trajectories the two center Dirac equation is solved numerically with B-Splines. The solutions form a quasi complete set of basis functions at each instant of time. By means of coupled-channel calculations we perform the time evolution of the system, i.e. the transition from one basis set to another. Results are obtained in the monopole approximation in which only a monopole contribution of the potential is used in the Dirac equation.

  17. Design Considerations for High Energy Electron -- Positron Storage Rings

    Science.gov (United States)

    Richter, B.

    1966-11-01

    High energy electron-positron storage rings give a way of making a new attack on the most important problems of elementary particle physics. All of us who have worked in the storage ring field designing, building, or using storage rings know this. The importance of that part of storage ring work concerning tests of quantum electrodynamics and mu meson physics is also generally appreciated by the larger physics community. However, I do not think that most of the physicists working tin the elementary particle physics field realize the importance of the contribution that storage ring experiments can make to our understanding of the strongly interacting particles. I would therefore like to spend the next few minutes discussing the sort of things that one can do with storage rings in the strongly interacting particle field.

  18. Pumping Electron-Positron Pairs from a Well Potential

    Science.gov (United States)

    Wang, Qiang; Liu, Jie; Fu, Li-bin

    2016-01-01

    In the presence of very deep well potential, electrons will spontaneously occupy the empty embedded bound states and electron-positron pairs are created by means of a non-perturbative tunneling process. In this work, by slowly oscillating the width or depth, the population transfer channels are opened and closed periodically. We find and clearly show that by the non-synchronous ejections of particles, the saturation of pair number in a static super-critical well can be broken, and electrons and positrons can be pumped inexhaustibly from vacuum with a constant production rate. In the adiabatic limit, final pair number after a single cycle has quantized values as a function of the upper boundary of the oscillating, and the critical upper boundaries indicate the diving points of the bound states. PMID:27125998

  19. Electron-positron pair production in inhomogeneous electromagnetic fields

    CERN Document Server

    Kohlfürst, Christian

    2015-01-01

    The process of electron-positron pair production is investigated within the phase-space Wigner formalism. The similarities between atomic ionization and pair production for homogeneous, but time-dependent linearly polarized electric fields are examined mainly in the regime of multiphoton absorption (field-dependent threshold, above-threshold pair production). Characteristic signatures in the particle spectra are identified (effective mass, channel closing). The non-monotonic dependence of the particle yield on the carrier frequency is discussed as well. The investigations are then extended to spatially inhomogeneous electric fields. New effects arising due to the spatial dependence of the effective mass are discussed in terms of a semi-classical interpretation. An increase in the normalized particle yield is found for various field configurations. Pair production in inhomogeneous electric and magnetic fields is also studied. The influence of a time-dependent spatially inhomogeneous magnetic field on the momen...

  20. Simulation of electron-positron convertor for SPring-8

    International Nuclear Information System (INIS)

    In the SPring-8, we are planning to use positrons in order to increase the beam life time in a storage-ring. These positrons are producted at a electron-positron convertor in a linac. In this report, we presented simulations about conversion efficiency of the convertor with various magnetic fields of the convertor system. We constructed the test apparatus of convertor in Tokai establishment, JAERI. But in this report, we also simulated with the conditions which are not available in the apparatus, so as to cover the results of experiments. And we found the best constitution of magnetic fields for the convertor. The conversion efficiency is up to 0.27% with the best magnetic fields. The aim of this report is to help designing the positron-electron convertor of the SPring-8 linac. (author)

  1. Precursors and electron-positron pair loading from erupting fireballs

    CERN Document Server

    Ramirez-Ruiz, E; Lazzati, D; Ramirez-Ruiz, Enrico; Fadyen, Andrew I. Mac; Lazzati, Davide

    2002-01-01

    Recent observations suggest that long-duration gamma-ray bursts and their afterglows are produced by highly relativistic jets emitted in core-collapse explosions. As the jet makes its way out of the stellar mantle, a bow shock runs ahead and a strong thermal precursor is produced as the shock breaks out. Such erupting fireballs produce a very bright gamma-ray precursor as they interact with the thermal break-out emission. The prompt gamma-ray emission propagates ahead of the fireball before it becomes optically thin, leading to electron-positron pair loading and radiative acceleration of the external medium. The detection of such precursors would offer the possibility of diagnosing not only the radius of the stellar progenitor and the initial Lorentz factor of the collimated fireball, but also the density of the external environment.

  2. Electron-positron pair creation characterized by the conversion energy

    CERN Document Server

    Sitiwaldi, Ibrahim; Xie, Bai-Song

    2016-01-01

    It is demonstrated that a pair can be characterized under which mechanism it was created according to its conversion energy, a quantity defined as the sum of electron and its conjugate positron's mass-energy, in the study of electron-positron pair creation. The value of this quantity is checked with quantum field theoretical simulations for several field configurations and found that it can describe the creation process with rich physical picture, showing all the creation channels and giving the yields of each channel specifically. Evenly as a very convenient and powerful detection quantity it can be applicable to some complicated pair creation processes such as that triggered by cooperation of two different photons as well as the dynamically assisted Schwinger mechanism.

  3. Higgs shifts from electron-positron annihilations near neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Wegner, Gary A. [Dartmouth College, Department of Physics and Astronomy, Hanover, NH (United States); Onofrio, Roberto [Universita di Padova, Dipartimento di Fisica e Astronomia ' Galileo Galilei' , Padova (Italy); ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)

    2015-07-15

    We discuss the potential for using neutron stars to determine bounds on the Higgs-Kretschmann coupling by looking at peculiar shifts in gamma-ray spectroscopic features. In particular, we reanalyze multiple lines observed in GRB781119 detected by two gamma-ray spectrometers, and derive an upper bound on the Higgs-Kretschmann coupling that is much more constraining than the one recently obtained from white dwarfs. This calls for targeted analyses of spectra of gamma-ray bursts from more recent observatories, dedicated searches for differential shifts on electron-positron and proton-antiproton annihilation spectra in proximity of compact sources, and signals of electron and proton cyclotron lines from the same neutron star. (orig.)

  4. Nonlinear electromagnetic waves in a degenerate electron-positron plasma

    Energy Technology Data Exchange (ETDEWEB)

    El-Labany, S.K., E-mail: skellabany@hotmail.com [Department of Physics, Faculty of Science, Damietta University, New Damietta (Egypt); El-Taibany, W.F., E-mail: eltaibany@hotmail.com [Department of Physics, College of Science for Girls in Abha, King Khalid University, Abha (Saudi Arabia); El-Samahy, A.E.; Hafez, A.M.; Atteya, A., E-mail: ahmedsamahy@yahoo.com, E-mail: am.hafez@sci.alex.edu.eg, E-mail: ahmed_ateya2002@yahoo.com [Department of Physics, Faculty of Science, Alexandria University, Alexandria (Egypt)

    2015-08-15

    Using the reductive perturbation technique (RPT), the nonlinear propagation of magnetosonic solitary waves in an ultracold, degenerate (extremely dense) electron-positron (EP) plasma (containing ultracold, degenerate electron, and positron fluids) is investigated. The set of basic equations is reduced to a Korteweg-de Vries (KdV) equation for the lowest-order perturbed magnetic field and to a KdV type equation for the higher-order perturbed magnetic field. The solutions of these evolution equations are obtained. For better accuracy and searching on new features, the new solutions are analyzed numerically based on compact objects (white dwarf) parameters. It is found that including the higher-order corrections results as a reduction (increment) of the fast (slow) electromagnetic wave amplitude but the wave width is increased in both cases. The ranges where the RPT can describe adequately the total magnetic field including different conditions are discussed. (author)

  5. Nonlinear electromagnetic waves in a degenerate electron-positron plasma

    International Nuclear Information System (INIS)

    Using the reductive perturbation technique (RPT), the nonlinear propagation of magnetosonic solitary waves in an ultracold, degenerate (extremely dense) electron-positron (EP) plasma (containing ultracold, degenerate electron, and positron fluids) is investigated. The set of basic equations is reduced to a Korteweg-de Vries (KdV) equation for the lowest-order perturbed magnetic field and to a KdV type equation for the higher-order perturbed magnetic field. The solutions of these evolution equations are obtained. For better accuracy and searching on new features, the new solutions are analyzed numerically based on compact objects (white dwarf) parameters. It is found that including the higher-order corrections results as a reduction (increment) of the fast (slow) electromagnetic wave amplitude but the wave width is increased in both cases. The ranges where the RPT can describe adequately the total magnetic field including different conditions are discussed. (author)

  6. Present status of KEK electron/positron Linac

    International Nuclear Information System (INIS)

    The Electron/Positron Linac injects electron and positron beams into four different rings; KEKB High Energy Ring(electron 8GeV), KBKB Low Energy Ring(positron 3.45 GeV), PF(electron 2.5 GeV), PF-AR(electron 2.5 GeV). During the summer shutdown of 1999, many improvements such as upgrade of an SHB1 power supply, installation of a new SHB2 cavity with an improved cooling channel, introduction of a new workstation for feedback systems etc.. Stability of the linac has been improved and beam switching among these rings is performed in a short time. Operation time of the linac during FY 1999 was 7,296 hours. Statistics of linac operation and activities for obtaining high reliability of the linac are presented. (author)

  7. Asymmetric collider

    International Nuclear Information System (INIS)

    The study of CP violation in beauty decay is one of the key challenges facing high energy physics. Much work has not yielded a definitive answer how this study might best be performed. However, one clear conclusion is that new accelerator facilities are needed. Proposals include experiments at asymmetric electron-positron colliders and in fixed-target and collider modes at LHC and SSC. Fixed-target and collider experiments at existing accelerators, while they might succeed in a first observation of the effect, will not be adequate to study it thoroughly. Giomataris has emphasized the potential of a new approach to the study of beauty CP violation: the asymmetric proton collider. Such a collider might be realized by the construction of a small storage ring intersecting an existing or soon-to-exist large synchrotron, or by arranging collisions between a large synchrotron and its injector. An experiment at such a collider can combine the advantages of fixed-target-like spectrometer geometry, facilitating triggering, particle identification and the instrumentation of a large acceptance, while the increased √s can provide a factor > 100 increase in beauty-production cross section compared to Tevatron or HERA fixed-target. Beams crossing at a non-zero angle can provide a small interaction region, permitting a first-level decay-vertex trigger to be implemented. To achieve large √s with a large Lorentz boost and high luminosity, the most favorable venue is the high-energy booster (HEB) at the SSC Laboratory, though the CERN SPS and Fermilab Tevatron are also worth considering

  8. Methods of extracting electron-positron enhancement factors from experimental ACAR data

    International Nuclear Information System (INIS)

    Methods of extracting the full shape of the electron-positron momentum density from experimental angular correlation of positron annihilation radiation curves are discussed. The proposed analysis of experimental data allows more reliable verification of the form of electron-positron enhancement factors near the Fermi surface in simple metals. (author). 14 refs, 2 figs

  9. Electromagnetic cascade in high energy electron, positron, and photon interactions with intense laser pulses

    CERN Document Server

    Bulanov, S S; Esarey, E; Leemans, W P

    2013-01-01

    The interaction of high energy electrons, positrons, and photons with intense laser pulses is studied in head-on collision geometry. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution, which suppresses the emission of high energy photons, thus reducing the number of electron-positron pairs being generated. Therefore, this type of interaction suppresses the development of the electromagnetic avalanche-type discharge, i.e., the exponential growth of the number of electrons, positrons, and photons does not occur in the course of interaction. The suppression will occur when 3D effects can be neglected in the transverse particle orbits, i.e., for sufficiently broad laser pulses with intensities that are not too extreme. The final distributions of electrons, positrons, and...

  10. Measurement of the cross-section of electron-positron scattering at high energy and quantum electrodynamics testing

    International Nuclear Information System (INIS)

    The experiment we have performed on the ACO (Orsay Collider Ring) is one of the most accurate tests of quantum electrodynamics over very short interaction distances (10-14 cm). We have studied the electron-positron elastic scattering at very wide angle. This work is divided into 4 parts. The first part reviews recent tests of quantum electrodynamics and presents the electron-positron elastic scattering. The second part describes the measurement of brightness: the experimental device, data analysis and accuracy. The measurement of brightness has been performed by detecting the photons emitted in the double Bremsstrahlung reaction: e+e- → e+e-γγ. The third part deals with the measurement of the number of Bhabha events. The last part compares the experimental value of the Bhabha scattering with the theoretically expected value. We have got the following results: the number of Bhabha events: 757 events, the experimental value for Bhabha scattering cross-section: [1.97 ± 0.09 (stat.) ± 0.10 (syst.)]*10-31 cm2. The comparison of this experimental value with the expected value has allowed us to set the lower limit of the cutting parameter Λ: Λ > 2 GeV

  11. German lab unveils plan to build physicists' next collider

    CERN Multimedia

    Abott, A

    2001-01-01

    An international team of physicists are to propose the construction of a major collider. 'TESLA' - the 'Tera electron volt Energy Superconducting Linear Accelerator' will be a linear electron-positron collider based on superconducting resonators. It will be based at DESY and cost around three billion US dollars (2 pages).

  12. Propagation of localized structures in relativistic magnetized electron-positron plasmas using particle-in-cell simulations

    International Nuclear Information System (INIS)

    We use a particle-in-cell simulation to study the propagation of localized structures in a magnetized electron-positron plasma with relativistic finite temperature. We use as initial condition for the simulation an envelope soliton solution of the nonlinear Schrödinger equation, derived from the relativistic two fluid equations in the strongly magnetized limit. This envelope soliton turns out not to be a stable solution for the simulation and splits in two localized structures propagating in opposite directions. However, these two localized structures exhibit a soliton-like behavior, as they keep their profile after they collide with each other due to the periodic boundary conditions. We also observe the formation of localized structures in the evolution of a spatially uniform circularly polarized Alfvén wave. In both cases, the localized structures propagate with an amplitude independent velocity

  13. Propagation of localized structures in relativistic magnetized electron-positron plasmas using particle-in-cell simulations

    Energy Technology Data Exchange (ETDEWEB)

    López, Rodrigo A. [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción 4070386 (Chile); Muñoz, Víctor [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Viñas, Adolfo F. [Geospace Physics Laboratory, Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States); Valdivia, Juan A. [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y la Nanotecnología (CEDENNA), Santiago 9170124 (Chile)

    2015-09-15

    We use a particle-in-cell simulation to study the propagation of localized structures in a magnetized electron-positron plasma with relativistic finite temperature. We use as initial condition for the simulation an envelope soliton solution of the nonlinear Schrödinger equation, derived from the relativistic two fluid equations in the strongly magnetized limit. This envelope soliton turns out not to be a stable solution for the simulation and splits in two localized structures propagating in opposite directions. However, these two localized structures exhibit a soliton-like behavior, as they keep their profile after they collide with each other due to the periodic boundary conditions. We also observe the formation of localized structures in the evolution of a spatially uniform circularly polarized Alfvén wave. In both cases, the localized structures propagate with an amplitude independent velocity.

  14. Design of an 18 MW Beam Dump for 500 GeV Electron/Positron Beams at an ILC

    CERN Document Server

    Amann, John; Seryi, Andrei; Walz, Dieter; Kulkarni, Kiran; Rai, Pravin; Satyamurthy, Polepalle; Tiwari, Vikar; Vincke, Heinz

    2010-01-01

    This article presents a report on the progress made in designing 18 MW water based Beam Dumps for electrons or positrons for an International Linear Collider (ILC). Multi-dimensional technology issues have to be addressed for the successful design of the Beam Dump. They include calculations of power deposition by the high energy electron/positron beam bunch trains, computational fluid dynamic analysis of turbulent water flow, mechanical design, process flow analysis, hydrogen/oxygen recombiners, handling of radioactive 7Be and 3H, design of auxiliary equipment, provisions for accident scenarios, remote window exchanger, radiation shielding, etc. The progress made to date is summarized, the current status, and also the issues still to be addressed

  15. A Model of Electron-Positron Pair Formation

    Directory of Open Access Journals (Sweden)

    Lehnert B.

    2008-01-01

    Full Text Available The elementary electron-positron pair formation process is considered in terms of a revised quantum electrodynamic theory, with special attention to the conservation of energy, spin, and electric charge. The theory leads to a wave-packet photon model of narrow line width and needle-radiation properties, not being available from conventional quantum electrodynamics which is based on Maxwell’s equations. The model appears to be consistent with the observed pair production process, in which the created electron and positron form two rays that start within a very small region and have original directions along the path of the incoming photon. Conservation of angular momentum requires the photon to possess a spin, as given by the present theory but not by the conventional one. The nonzero electric field divergence further gives rise to a local intrinsic electric charge density within the photon body, whereas there is a vanishing total charge of the latter. This may explain the observed fact that the photon decays on account of the impact from an external electric field. Such a behaviour should not become possible for a photon having zero local electric charge density.

  16. Correlated electron-positron emission in heavy-ion collisions

    International Nuclear Information System (INIS)

    A group of narrow electron-positron sum-energy lines with similar mean energies around 610, 750 and 810 keV has been observed with the EPOS spectrometer in both collision systems 238U + 232Th and 238U + 181Ta studied so far at the UNILAC heavy ion accelerator of GSI, Darmstadt. The intensities of the three lines vary with the beam-energy, the variation being most clearly observed for the 748-keV line in 238U + 181Ta. On the basis of our present understanding Internal Pair Conversion in a collision product at rest or in flight as well as coincident lepton emission during the quasiatomic phase of the collision can be excluded as the origin. The very narrow widths of the sum-energy lines as compared to the widths of the associated broad structure in the difference spectrum of the lepton energies seem to argue for a mutual cancellation of kinematical shifts. Such correlation is expected for two leptons emitted back-to-back in a two-body decay of objects being at rest in the heavy-ion c.m. frame. This speculative hypothesis is confronted with the actual dependence of the lines on the individual lepton energy and the lepton emission angle, as well as on the opening angle of the pair. In fact, the back-to-back decay could not be proved to be a general feature of these lines. (orig.)

  17. A Model of Electron-Positron Pair Formation

    Directory of Open Access Journals (Sweden)

    Lehnert B.

    2008-01-01

    Full Text Available The elementary electron-positron pair formation process is consideredin terms of a revised quantum electrodynamic theory, with specialattention to the conservation of energy, spin, and electric charge.The theory leads to a wave-packet photon model of narrow line widthand needle-radiation properties, not being available from conventionalquantum electrodynamics which is based on Maxwell's equations. Themodel appears to be consistent with the observed pair productionprocess, in which the created electron and positron form two raysthat start within a very small region and have original directionsalong the path of the incoming photon. Conservation of angular momentum requires the photon to possess a spin, as given by the present theory but not by the conventional one. The nonzero electric field divergence further gives rise to a local intrinsic electric charge density within the photon body, whereas there is a vanishing total charge of the latter. This may explain the observed fact that the photon decays on account of the impact from an external electric field. Such a behaviour should not become possible for a photon having zero local electric charge density.

  18. Strongly Enhanced Stimulated Brillouin Backscattering in an Electron-Positron Plasma

    Science.gov (United States)

    Edwards, Matthew R.; Fisch, Nathaniel J.; Mikhailova, Julia M.

    2016-01-01

    Stimulated Brillouin backscattering of light is shown to be drastically enhanced in electron-positron plasmas, in contrast to the suppression of stimulated Raman scattering. A generalized theory of three-wave coupling between electromagnetic and plasma waves in two-species plasmas with arbitrary mass ratios, confirmed with a comprehensive set of particle-in-cell simulations, reveals violations of commonly held assumptions about the behavior of electron-positron plasmas. Specifically, in the electron-positron limit three-wave parametric interaction between light and the plasma acoustic wave can occur, and the acoustic wave phase velocity differs from its usually assumed value.

  19. Electron-positron physics at 1 TeV

    International Nuclear Information System (INIS)

    We discuss the motivation for TeV e+ e/sup /minus// linear colliders, some aspects of their design, and the experimental consequences that follow from the design. After a brief discussion of the general physics environment, we consider the discovery potential of these colliders by examining three sample processes: the detection of new heavy leptons, standard Higgs bosons, and charged Higgs bosons. 13 refs., 22 figs., 5 tabs

  20. Cross section formulae on single W and Z boson productions in electron-positron collisions

    International Nuclear Information System (INIS)

    The formulae are given for the transverse momentum distributions and total cross sections for the single W boson and Z boson productions in electron-positron collisions by using the equivalent photon approximation. (author)

  1. Jet cross sections in electron-positron annihilation

    International Nuclear Information System (INIS)

    There are few, if any, detailed tests of QCD at present. I disucss the problems associated with testing QCD and argue that the three jet angular distribution in electron-positron annihilation is a good quantity to use because it minimizes the sensitivity to nonperturbative effects and provides a test of the detailed structure of QCD. However, for such a test to be possible, the perturbation expansion must be well behaved. I present a calculation of the perturbative corrections using two different generalizations of the Sterman-Weinberg two-jet cross section. I argue that because of the uncertainties in our understanding of hadronization it is necessary that the corrections to both these cross sections be small. In presenting the results I use the recent proof of Mukti and Sterman that all the logarithms can be resummed. I find that at Z-factory energies there is a substantial region of parameters defining the jets for which the correction is small, but that there is no such region at PEP/PETRA energies. This problem at PEP/PETRA energies is made worse by the results of a study of the effects of hadronization. Using a simple model I find very significant effects at PEP/PETRA energies that would make a test difficult. These effects do not, however, present problems at Z-factory energies. I conclude that, even if there are further theoretical advances, testing QCD at PEP/PETRA energies using the three-jet angular distribution will be very difficult. However, this distribution can be used to test QCD in a detailed way at Z-factory energies. The corrected results, furthermore, show a systematic difference from the lowest order result that may be measurable at Z-factory energies. If this effect could be measured it would provide a yet more detailed test of QCD, testing, for example, the three gluon coupling. 66 references

  2. Physics goals of the next linear collider

    International Nuclear Information System (INIS)

    We present the prospects for the next generation of high-energy physics experiments with electron-positron colliding beams. This report summarizes the current status of the design and technological basis of a linear collider of center of mass energy 500 GeV-1.5 TeV, and the opportunities for high-energy physics experiments that this machine is expected to open. 132 refs., 54 figs., 14 tabs

  3. Wakefields generated by collisional neutrinos in neutral-electron-positron-ion plasma

    Energy Technology Data Exchange (ETDEWEB)

    Tinakiche, Nouara [Faculty of Sciences, Department of Physics, University of Boumeredes U.M.B.B., Boumerdes 35000 (Algeria)

    2015-12-15

    A classical fluid description is adopted to investigate nonlinear interaction between an electron-type neutrino beam and a relativistic collisionless unmagnetized neutral-electron-positron-ion plasma. In this work, we consider the collisions of the neutrinos with neutrals in the plasma and study their effect on the generation of wakefields in presence of a fraction of ions in a neutral-electron-positron plasma. The results obtained in the present work are interpreted and compared with previous studies.

  4. Wakefields generated by collisional neutrinos in neutral-electron-positron-ion plasma

    International Nuclear Information System (INIS)

    A classical fluid description is adopted to investigate nonlinear interaction between an electron-type neutrino beam and a relativistic collisionless unmagnetized neutral-electron-positron-ion plasma. In this work, we consider the collisions of the neutrinos with neutrals in the plasma and study their effect on the generation of wakefields in presence of a fraction of ions in a neutral-electron-positron plasma. The results obtained in the present work are interpreted and compared with previous studies

  5. Two-site Hubbard molecule with a spinless electron-positron pair

    KAUST Repository

    Cossu, F.

    2012-12-19

    We determine the eigenvalues of the two-site Hubbard molecule with one electron and one positron to describe the characteristics of electron-positron interactions in solids. While the effect of hopping is, in general, opposite to the effect of on-site interaction, we find a complex scenario for the electron-positron pair with a non-vanishing potential drop. We give analytical solutions and discuss the combined effects of the model parameters.

  6. Kinetic effects on streaming instabilities in electron-positron-ion plasmas

    Science.gov (United States)

    Shan, S. Ali; Saleem, H.

    2009-02-01

    Streaming instabilities in electron-positron-ion plasmas are investigated using kinetic approach in several different limits. The effects of the variation of background temperatures of electrons Teo and positrons Tpo on the growth rates are also presented for the case of ion beam streaming into electron-positron plasmas and positrons beam streaming into electron-ion plasmas. It is noticed that the increase of number density of positrons gives a destabilizing trend to the electrostatic perturbations in the system.

  7. Coupled channel calculations for electron-positron pair production in collisions of heavy ionsThis work is part of the doctoral thesis of Matthias Gail, Giessen (D26) 2001.

    Science.gov (United States)

    Gail, Matthias; Grün, Norbert; Scheid, Werner

    2003-04-01

    Coupled channel calculations are performed for electron-positron pair production in relativistic collisions of heavy ions. For this purpose the wavefunction is expanded into different types of basis sets consisting of atomic wavefunctions centred around the projectile ion only and around both of the colliding nuclei. The results are compared with experimental data from Belkacem et al (1997 Phys. Rev. A 56 2807). This work is part of the doctoral thesis of Matthias Gail, Giessen (D26) 2001.

  8. Searching for Lepton Flavor Violation at a Future High Energy Electron-Positron Collider

    OpenAIRE

    Murakami, Brandon; Tim M.P. Tait(Department of Physics, University of California Irvine, Irvine, CA 92697, U.S.A.)

    2014-01-01

    We consider theories where lepton flavor is violated, in particular concentrating on the four fermion operator consisting of three electrons and a tau. Strong constraints are available from existing searches for tau -> eee, requiring the scale of the contact interaction to be less than ~(9 TeV)^-2. We reexamine this type of physics, assuming that the particles responsible are heavy (with masses greater than ~TeV) such that a contact interaction description continues to be applicable at the en...

  9. An electron-positron linear collider as a B-antiB-meson factory

    International Nuclear Information System (INIS)

    In this note a new scheme of machine is proposed, based on improved superconducting cavity technology. A ''threshold machine'' is chosen since the possibility of selecting the B-meson type is considered

  10. Challenges in future linear colliders

    CERN Document Server

    Chattopadhyay, S

    2002-01-01

    For decades, electron-positron colliders have been complementing proton-proton colliders. But the circular LEP, the largest e/sup -/e /sup +/ collider, represented an energy limit beyond which energy losses to synchrotron radiation necessitate moving to e/sup -/e/sup + / linear colliders (LCs), thereby raising new challenges for accelerator builders. Japanese-American, German, and European collaborations have presented options for the "Future Linear Collider " (FLC). Key accelerator issues for any FLC option are the achievement of high enough energy and luminosity. Damping rings, taking advantage of the phenomenon of synchrotron radiation, have been developed as the means for decreasing beam size, which is crucial for ensuring a sufficiently high rate of particle-particle collisions. Related challenges are alignment and stability in an environment where even minute ground motion can disrupt performance, and the ability to monitor beam size. The technical challenges exist within a wider context of socioeconomi...

  11. Luminosity Limitations in Linear Colliders Based on Plasma Acceleration

    CERN Document Server

    Lebedev, Valeri; Nagaitsev, Sergei

    2016-01-01

    Particle acceleration in plasma creates a possibility of exceptionally high accelerating gradients and appears as a very attractive option for future linear electron-positron and/or photon-photon colliders. These high accelerating gradients were already demonstrated in a number of experiments. However, a linear collider requires exceptionally high beam brightness which still needs to be demonstrated. In this article we discuss major phenomena which limit the beam brightness of accelerated beam and, consequently, the collider luminosity.

  12. Search for high mass resonances decaying into electron-positron pairs in proton-proton collisions at √(s)=7 TeV with the ATLAS detector

    International Nuclear Information System (INIS)

    The Standard Model of particle physics was developed to describe the fundamental particles, which form matter, and their interactions via the strong, electromagnetic and weak force. Although most measurements are described with high accuracy, some observations indicate that the Standard Model is incomplete. Numerous extensions were developed to solve these limitations. Several of these extensions predict heavy resonances, so-called Z' bosons, that can decay into an electron positron pair. The particle accelerator Large Hadron Collider (LHC) at CERN in Switzerland was built to collide protons at unprecedented center-of-mass energies, namely 7 TeV in 2011. With the data set recorded in 2011 by the ATLAS detector, a large multi-purpose detector located at the LHC, the electron positron pair mass spectrum was measured up to high masses in the TeV range. The properties of electrons and the probability that other particles are mis-identified as electrons were studied in detail. Using the obtained information, a sophisticated Standard Model expectation was derived with data-driven methods and Monte Carlo simulations. In the comparison of the measurement with the expectation, no significant deviations from the Standard Model expectations were observed. Therefore exclusion limits for several Standard Model extensions were calculated. For example, Sequential Standard Model (SSM) Z' bosons with masses below 2.10 TeV were excluded with 95% Confidence Level (C.L.).

  13. Search for high mass resonances decaying into electron-positron pairs in proton-proton collisions at {radical}(s)=7 TeV with the ATLAS detector

    Energy Technology Data Exchange (ETDEWEB)

    Goeringer, Christian

    2013-04-25

    The Standard Model of particle physics was developed to describe the fundamental particles, which form matter, and their interactions via the strong, electromagnetic and weak force. Although most measurements are described with high accuracy, some observations indicate that the Standard Model is incomplete. Numerous extensions were developed to solve these limitations. Several of these extensions predict heavy resonances, so-called Z' bosons, that can decay into an electron positron pair. The particle accelerator Large Hadron Collider (LHC) at CERN in Switzerland was built to collide protons at unprecedented center-of-mass energies, namely 7 TeV in 2011. With the data set recorded in 2011 by the ATLAS detector, a large multi-purpose detector located at the LHC, the electron positron pair mass spectrum was measured up to high masses in the TeV range. The properties of electrons and the probability that other particles are mis-identified as electrons were studied in detail. Using the obtained information, a sophisticated Standard Model expectation was derived with data-driven methods and Monte Carlo simulations. In the comparison of the measurement with the expectation, no significant deviations from the Standard Model expectations were observed. Therefore exclusion limits for several Standard Model extensions were calculated. For example, Sequential Standard Model (SSM) Z' bosons with masses below 2.10 TeV were excluded with 95% Confidence Level (C.L.).

  14. Search for high mass resonances decaying into electron-positron pairs in proton-proton collisions at $\\sqrt{s}$ = 7 TeV with the ATLAS detector

    CERN Document Server

    Goeringer, Christian

    The Standard Model of particle physics was developed to describe the fundamental particles, which form matter, and their interactions via the strong, electromagnetic and weak force. Although most measurements are described with high accuracy, some observations indicate that the Standard Model is incomplete. Numerous extensions were developed to solve these limitations. Several of these extensions predict heavy resonances, so-called Z' bosons, that can decay into an electron positron pair. The particle accelerator Large Hadron Collider (LHC) at CERN in Switzerland was built to collide protons at unprecedented center-of-mass energies, namely 7 TeV in 2011. With the data set recorded in 2011 by the ATLAS detector, a large multi-purpose detector located at the LHC, the electron positron pair mass spectrum was measured up to high masses in the TeV range. The properties of electrons and the probability that other particles are mis-identified as electrons were studied in detail. Using the obtained information, a ...

  15. Propagation and interaction of ion-acoustic solitary waves in a quantum electron-positron-ion plasma

    Institute of Scientific and Technical Information of China (English)

    Han Jiu-Ning; Luo Jun-Hua; Sun Gui-Hua; Liu Zhen-Lai; Li Shou-Yi

    2011-01-01

    This paper discusses the existence of ion-acoustic solitary waves and their interaction in a dense quantum electron-positron-ion plasma by using the quantum hydrodynamic equations. The extended Poincaré-Lighthill-Kuo perturbation method is used to derive the Korteweg-de Vries equations for quantum ion-acoustic solitary waves in this plasma. The effects of the ratio of positrons to ions unperturbation number density p and the quantum diffraction parameter He (Hp) on the newly formed wave during interaction, and the phase shift of the colliding solitary waves are studied. It is found that the interaction between two solitary waves fits linear superposition principle and these plasma parameters have significantly influence on the newly formed wave and phase shift of the colliding solitary waves. The investigations should be useful for understanding the propagation and interaction of ion-acoustic solitary waves in dense astrophysical plasmas (such as white dwarfs) as well as in intense laser-solid matter interaction experiments.

  16. A Monte-Carlo simulation of the equilibrium beam polarization in ultra-high energy electron (positron) storage rings

    International Nuclear Information System (INIS)

    With the recently emerging global interest in building a next generation of circular electron-positron colliders to study the properties of the Higgs boson, and other important topics in particle physics at ultra-high beam energies, it is also important to pursue the possibility of implementing polarized beams at this energy scale. It is therefore necessary to set up simulation tools to evaluate the beam polarization at these ultra-high beam energies. In this paper, a Monte-Carlo simulation of the equilibrium beam polarization based on the Polymorphic Tracking Code(PTC) (Schmidt et al., 2002) is described. The simulations are for a model storage ring with parameters similar to those of proposed circular colliders in this energy range, and they are compared with the suggestion (Derbenev et al., 1978) that there are different regimes for the spin dynamics underlying the polarization of a beam in the presence of synchrotron radiation at ultra-high beam energies. In particular, it has been suggested that the so-called ''correlated'' crossing of spin resonances during synchrotron oscillations at current energies, evolves into ''uncorrelated'' crossing of spin resonances at ultra-high energies.

  17. Electromagnetic cascade in high-energy electron, positron, and photon interactions with intense laser pulses

    Science.gov (United States)

    Bulanov, S. S.; Schroeder, C. B.; Esarey, E.; Leemans, W. P.

    2013-06-01

    The interaction of high-energy electrons, positrons, and photons with intense laser pulses is studied in head-on collision geometry. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution, which suppresses the emission of high-energy photons, thus reducing the number of electron-positron pairs being generated. Therefore, this type of interaction suppresses the development of the electromagnetic avalanche-type discharge, i.e., the exponential growth of the number of electrons, positrons, and photons does not occur in the course of interaction. The suppression will occur when three-dimensional effects can be neglected in the transverse particle orbits, i.e., for sufficiently broad laser pulses with intensities that are not too extreme. The final distributions of electrons, positrons, and photons are calculated for the case of a high-energy e-beam interacting with a counterstreaming, short intense laser pulse. The energy loss of the e-beam, which requires a self-consistent quantum description, plays an important role in this process, as well as provides a clear experimental observable for the transition from the classical to quantum regime of interaction.

  18. Birth of colliding beams in Europe, two photon studies at Adone

    CERN Document Server

    Bonolis, Luisa

    2015-01-01

    This article recalls the birth of the first electron-positron storage ring AdA, and the construction of the higher energy collider ADONE, where early photon-photon collisions were observed. The events which led the Austrian physicist Bruno Touschek to propose and construct AdA will be recalled, starting with early work on the Wideroe's betatron during World War II, up to the construction of ADONE, and the theoretical contribution to radiative corrections to electron-positron collisions.

  19. Generation of neutral and high-density electron-positron pair plasmas in the laboratory.

    Science.gov (United States)

    Sarri, G; Poder, K; Cole, J M; Schumaker, W; Di Piazza, A; Reville, B; Dzelzainis, T; Doria, D; Gizzi, L A; Grittani, G; Kar, S; Keitel, C H; Krushelnick, K; Kuschel, S; Mangles, S P D; Najmudin, Z; Shukla, N; Silva, L O; Symes, D; Thomas, A G R; Vargas, M; Vieira, J; Zepf, M

    2015-01-01

    Electron-positron pair plasmas represent a unique state of matter, whereby there exists an intrinsic and complete symmetry between negatively charged (matter) and positively charged (antimatter) particles. These plasmas play a fundamental role in the dynamics of ultra-massive astrophysical objects and are believed to be associated with the emission of ultra-bright gamma-ray bursts. Despite extensive theoretical modelling, our knowledge of this state of matter is still speculative, owing to the extreme difficulty in recreating neutral matter-antimatter plasmas in the laboratory. Here we show that, by using a compact laser-driven setup, ion-free electron-positron plasmas with unique characteristics can be produced. Their charge neutrality (same amount of matter and antimatter), high-density and small divergence finally open up the possibility of studying electron-positron plasmas in controlled laboratory experiments. PMID:25903920

  20. Future Circular Colliders

    CERN Document Server

    AUTHOR|(CDS)2108454; Zimmermann, Frank

    2015-01-01

    In response to a request from the 2013 Update of the European Strategy for Particle Physics, the global Future Circular Collider (FCC) study is preparing the foundation for a next-generation large-scale accelerator infrastructure in the heart of Europe. The FCC study focuses on the design of a 100-TeV hadron collider (FCC-hh), to be accommodated in a new ∼100 km tunnel near Geneva. It also includes the design of a high-luminosity electron-positron collider (FCC-ee), which could be installed in the same tunnel as a potential intermediate step, and a lepton-hadron collider option (FCC-he). The scope of the FCC study comprises accelerators, technology, infrastructure, detectors, physics, concepts for worldwide data services, international governance models, and implementation scenarios. Among the FCC core technologies figure 16-T dipole magnets, based on Nb3Sn superconductor, for the FCC-hh hadron collider, and a highly efficient superconducting radiofrequency system for the FCC-ee lepton collider. The interna...

  1. Future Circular Colliders

    CERN Document Server

    AUTHOR|(CDS)2108454; Zimmermann, Frank

    2015-01-01

    In response to a request from the 2013 Update of the European Strategy for Particle Physics, the global Future Circular Collider (FCC) study is preparing the foundation for a next-generation large-scale accelerator infrastructure in the heart of Europe. The FCC study focuses on the design of a 100-TeV hadron collider (FCC-hh), to be accommodated in a new ∼100 km tunnel near Geneva. It also includes the design of a high-luminosity electron-positron collider (FCC-ee), which could be installed in the same tunnel as a potential intermediate step, and a lepton-hadron collider option (FCC-he). The scope of the FCC study comprises accelerators, technology, infrastructure, detector, physics, concepts for worldwide data services, international governance models, and implementation scenarios. Among the FCC core technologies figure 16-T dipole magnets, based on Nb3Sn superconductor, for the FCC-hh hadron collider, and a highly efficient superconducting radiofrequency system for the FCC-ee lepton collider. The internat...

  2. Towards Future Circular Colliders

    CERN Document Server

    AUTHOR|(CDS)2108454; Zimmermann, Frank

    2015-01-01

    The Large Hadron Collider (LHC) at CERN presently provides proton-proton collisions at a centre-of-mass (c.m.) energy of 13 TeV. The LHC design was started more than 30 years ago, and its physics programme will extend through the second half of the 2030’s. The global Future Circular Collider (FCC) study is now preparing for a post-LHC project. The FCC study focuses on the design of a 100-TeV hadron collider (FCC-hh) in a new ∼100 km tunnel. It also includes the design of a high-luminosity electron-positron collider (FCC-ee) as a potential intermediate step, and a lepton-hadron collider option (FCC-he). The scope of the FCC study comprises accelerators, technology, infrastructure, detectors, physics, concepts for worldwide data services, international governance models, and implementation scenarios. Among the FCC core technologies figure 16-T dipole magnets, based on $Nb_3Sn$ superconductor, for the FCC-hh hadron collider, and a highly efficient superconducting radiofrequency system for the FCC-ee lepton c...

  3. Generation of a neutral, high-density electron-positron plasma in the laboratory

    CERN Document Server

    Sarri, G; Cole, J; Schumaker, W; Di Piazza, A; Reville, B; Doria, D; Dromey, B; Gizzi, L; Green, A; Grittani, G; Kar, S; Keitel, C H; Krushelnick, K; Kushel, S; Mangles, S; Najmudin, Z; Thomas, A G R; Vargas, M; Zepf, M

    2013-01-01

    We report on the laser-driven generation of purely neutral, relativistic electron-positron pair plasmas. The overall charge neutrality, high average Lorentz factor ($\\gamma_{e/p} \\approx 15$), small divergence ($\\theta_{e/p} \\approx 10 - 20$ mrad), and high density ($n_{e/p}\\simeq 10^{15}$cm$^{-3}$) of these plasmas open the pathway for the experimental study of the dynamics of this exotic state of matter, in regimes that are of relevance to electron-positron astrophysical plasmas.

  4. Luminosity Measurement at the International Linear Collider

    OpenAIRE

    Sadeh, Iftach

    2010-01-01

    The International Linear Collider (ILC) is a proposed electron-positron collider with a center-of-mass energy of 500~GeV, and a peak luminosity of $2 \\cdot 10^{34}~\\mathrm{cm}^{-2}\\mathrm{s}^{-1}$. The ILC will complement the Large Hadron Collider, a proton-proton accelerator, and provide precision measurements, which may help in solving some of the fundamental questions at the frontier of scientific research, such as the origin of mass and the possible existence of new principles of nature. ...

  5. On the effect of time-dependent inhomogeneous magnetic fields in electron-positron pair production

    Science.gov (United States)

    Kohlfürst, Christian; Alkofer, Reinhard

    2016-05-01

    Electron-positron pair production in space- and time-dependent electromagnetic fields is investigated. Especially, the influence of a time-dependent, inhomogeneous magnetic field on the particle momenta and the total particle yield is analyzed for the first time. The role of the Lorentz invariant E2 -B2, including its sign and local values, in the pair creation process is emphasized.

  6. Universality of multiplicity distribution in proton-proton and electron-positron collisions

    OpenAIRE

    Bzdak, Adam

    2015-01-01

    It is argued that the multiplicity distribution in proton-proton ($pp$) collisions, which is often parameterized by the negative binomial distribution, results from the multiplicity distribution measured in electron-positron ($e^{+}e^{-}$) collisions, once the fluctuating energy carried by two leading protons in $pp$ is taken into account.

  7. Tuning laser produced electron-positron jets for lab-astrophysics experiment

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hui [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Fiuza, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hazi, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kemp, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Link, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Pollock, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Marley, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nagel, S. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Park, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schneider, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shepherd, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tommasini, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wilks, S. C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Williams, G. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Barnak, D. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics (LLE); Chang, P-Y. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics (LLE); Fiksel, G. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics (LLE); Glebov, V. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics (LLE); Meyerhofer, D. D. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics (LLE); Myatt, J. F. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics (LLE); Stoeckel, C. [Univ. of Rochester, NY (United States). Lab. for Laser Energetics (LLE); Nakai, M. [Osaka Univ. (Japan). ILE; Arikawa, Y. [Osaka Univ. (Japan). ILE; Azechi, H. [Osaka Univ. (Japan). ILE; Fujioka, S. [Osaka Univ. (Japan). ILE; Hosoda, H. [Osaka Univ. (Japan). ILE; Kojima, S. [Osaka Univ. (Japan). ILE; Miyanga, N. [Osaka Univ. (Japan). ILE; Morita, T. [Osaka Univ. (Japan). ILE; Moritaka, T. [Osaka Univ. (Japan). ILE; Nagai, T. [Osaka Univ. (Japan). ILE; Namimoto, T. [Osaka Univ. (Japan). ILE; Nishimura, H. [Osaka Univ. (Japan). ILE; Ozaki, T. [Osaka Univ. (Japan). ILE; Sakawa, Y. [Osaka Univ. (Japan). ILE; Takabe, H. [Osaka Univ. (Japan). ILE; Zhang, Z. [Osaka Univ. (Japan). ILE

    2015-02-23

    This paper reviews the experiments on the laser produced electron-positron jets using large laser facilities worldwide. The goal of the experiments was to optimize the parameter of the pair jets for their potential applications in laboratory-astrophysical experiment. Results on tuning the pair jet’s energy, number, emittance and magnetic collimation will be presented.

  8. Nonlinear separate spin evolution in degenerate electron-positron-ion plasmas

    CERN Document Server

    Iqbal, Z

    2016-01-01

    The non-linear evolution of spin-electron acoustic, positron-acoustic, and spin-electron-positron acoustic waves is considered. It is demonstrated that weakly nonlinear dynamics of each wave leads to the soliton formation. Altogether, we report on existence of three different solitons. The spin-electron acoustic soliton known for electron-ion plasmas is described for electron-positron-ion plasmas for the first time. The existence of the spin-electron-positron acoustic soliton is reported for the first time. The positron-acoustic soliton and the spin-electron-positron acoustic soliton arise as the areas of a positive electric potential. The spin-electron acoustic soliton behaves as the area of a negative electric potential at the relatively small positron imbalance $n_{0p}/n_{0e}=0.1$ and as the area of a positive electric potential at the relatively large positron imbalance $n_{0p}/n_{0e}=0.5$.

  9. Neutrino production of electron-positron pairs at excited Landau levels in a strong magnetic field

    CERN Document Server

    Kuznetsov, A V; Savin, V N

    2014-01-01

    The process of neutrino production of electron positron pairs in a magnetic field of arbitrary strength, where electrons and positrons can be created in the states corresponding to excited Landau levels, is analysed. The mean value of the neutrino energy loss due to the process $\

  10. Photon Damping Caused by Electron-Positron Pair Production in a Strong Magnetic Field

    OpenAIRE

    Mikheev, N. V.; Chistyakov, M. V.

    2001-01-01

    Damping of an electromagnetic wave in a strong magnetic field is analyzed in the kinematic region near the threshold of electron-positron pair production. Damping of the electromagnetic field is shown to be noticeably nonexponential in this region. The resulting width of the photon $\\gamma \\to e^+ e^-$ decay is considerably smaller than previously known results.

  11. Localized structures of electromagnetic waves in hot electron-positron plasma

    International Nuclear Information System (INIS)

    The dynamics of relatively strong electromagnetic (EM) wave propagation in hot electron-positron plasma is investigated. The possibility of finding localized stationary structures of EM waves is explored. It it shown that under certain conditions the EM wave forms a stable localized soliton-like structures where plasma is completely expelled from the region of EM field location. (author). 9 refs, 2 figs

  12. Tuning laser produced electron-positron jets for lab-astrophysics experiment

    International Nuclear Information System (INIS)

    This paper reviews the experiments on the laser produced electron-positron jets using large laser facilities worldwide. The goal of the experiments was to optimize the parameter of the pair jets for their potential applications in laboratory-astrophysical experiment. Results on tuning the pair jet's energy, number, emittance and magnetic collimation will be presented.

  13. A precision luminosity monitor for use at electron - positron storage rings

    International Nuclear Information System (INIS)

    A precision luminosity monitor is described which has been used successfully in an experimental test of quantum electrodynamics at the 2.6GeV electron-positron storage ring(SPEAR-I)at the Stanford Linear Accelerator Center. Design considerations and construction details are given, together with a discussion of radiative corrections and an evaluation of the response of the monitor. (Auth.)

  14. Photon-photon colliders

    Energy Technology Data Exchange (ETDEWEB)

    Sessler, A.M.

    1995-04-01

    Since the seminal work by Ginsburg, et at., the subject of giving the Next Linear Collider photon-photon capability, as well as electron-positron capability, has drawn much attention. A 1990 article by V.I. Teinov describes the situation at that time. In March 1994, the first workshop on this subject was held. This report briefly reviews the physics that can be achieved through the photon-photon channel and then focuses on the means of achieving such a collider. Also reviewed is the spectrum of backscattered Compton photons -- the best way of obtaining photons. We emphasize the spectrum actually obtained in a collider with both polarized electrons and photons (peaked at high energy and very different from a Compton spectrum). Luminosity is estimated for the presently considered colliders, and interaction and conversion-point geometries are described. Also specified are laser requirements (such as wavelength, peak power, and average power) and the lasers that might be employed. These include conventional and free-electron lasers. Finally, we describe the R&D necessary to make either of these approaches viable and explore the use of the SLC as a test bed for a photon-photon collider of very high energy.

  15. Photon-photon colliders

    International Nuclear Information System (INIS)

    Since the seminal work by Ginsburg, et at., the subject of giving the Next Linear Collider photon-photon capability, as well as electron-positron capability, has drawn much attention. A 1990 article by V.I. Teinov describes the situation at that time. In March 1994, the first workshop on this subject was held. This report briefly reviews the physics that can be achieved through the photon-photon channel and then focuses on the means of achieving such a collider. Also reviewed is the spectrum of backscattered Compton photons -- the best way of obtaining photons. We emphasize the spectrum actually obtained in a collider with both polarized electrons and photons (peaked at high energy and very different from a Compton spectrum). Luminosity is estimated for the presently considered colliders, and interaction and conversion-point geometries are described. Also specified are laser requirements (such as wavelength, peak power, and average power) and the lasers that might be employed. These include conventional and free-electron lasers. Finally, we describe the R ampersand D necessary to make either of these approaches viable and explore the use of the SLC as a test bed for a photon-photon collider of very high energy

  16. Photon-photon colliders

    Energy Technology Data Exchange (ETDEWEB)

    Sessler, Andrew M.

    1996-01-01

    Since the seminal work by Ginsburg, et al., the subject of giving the Next Linear Collider photon-photon capability, as well as electron-positron capability, has drawn much attention [1]. A 1990 article by V.I. Telnov describes the situation at that time [2]. In March 1994, the first workshop on this subject was held [3]. This report briefly reviews the physics that can be achieved through the photon-photon channel and then focuses on the means of achieving such a collider. Also reviewed is the spectrum of backscattered Compton photons—the best way of obtaining photons. We emphasize the spectrum actually obtained in a collider with both polarized electrons and photons (peaked at high energy and very different from a Compton spectrum). Luminosity is estimated for the presently considered colliders, and interaction and conversion-point geometries are described. Also specified are laser requirements (such as wavelength, peak power, and average power) and the lasers that might be employed. These include conventional and free-electron lasers. Finally, we describe the R&D necessary to make either of these approaches viable and explore the use of the SLC as a test bed for a photon-photon collider of very high energy.

  17. The development of colliders

    International Nuclear Information System (INIS)

    Don Kerst, Gersh Budker, and Bruno Touschek were the individuals, and the motivating force, which brought about the development of colliders, while the laboratories at which it happened were Stanford, MURA, the Cambridge Electron Accelerator, Orsay, Frascati, CERN, and Novosibirsk. These laboratories supported, during many years, this rather speculative activity. Of course, many hundreds of physicists contributed to the development of colliders but the men who started it, set it in the right direction, and forcefully made it happen, were Don, Gersh, and Bruno. Don was instrumental in the development of proton-proton colliders, while Bruno and Gersh spearheaded the development of electron-positron colliders. In this brief review of the history, I will sketch the development of the concepts, the experiments, and the technological developments which made possible the development of colliders. It may look as if the emphasis is on theoretical concepts, but that is really not the case, for in this field -- the physics of beams -- the theory and experiment go hand in hand; theoretical understanding and advances are almost always motivated by the need to explain experimental results or the desire to construct better experimental devices

  18. Precision measurement of charged pion and kaon multiplicities in electron-positron annihilation at Q = 10.52 GeV

    CERN Document Server

    Leitgab, M; Perdekamp, M Grosse; Vossen, A; Adachi, I; Aihara, H; Asner, D M; Aulchenko, V; Aushev, T; Bakich, A M; Bhuyan, B; Bondar, A; Bozek, A; Bračko, M; Brodzicka, J; Browder, T E; Chekelian, V; Chen, A; Chen, P; Cheon, B G; Chilikin, K; Cho, K; Chobanova, V; Choi, Y; Cinabro, D; Dalseno, J; Drásal, Z; Dutta, D; Eidelman, S; Epifanov, D; Farhat, H; Fast, J E; Gaur, V; Gabyshev, N; Gillard, R; Giordano, F; Goh, Y M; Golob, B; Haba, J; Hayasaka, K; Hayashii, H; Hoshi, Y; Hou, W -S; Hsiung, Y B; Hyun, H J; Iijima, T; Ishikawa, A; Itoh, R; Jacobs, W W; Julius, T; Kang, J H; Kapusta, P; Kato, E; Kawasaki, T; Kim, H J; Kim, H O; Kim, J B; Kim, J H; Kim, M J; Klucar, J; Ko, B R; Kodyš, P; Kouzes, R T; Križan, P; Krokovny, P; Kumar, R; Kumita, T; Kwon, Y -J; Lange, J S; Lee, S -H; Li, Y; Liu, Z Q; Liventsev, D; Matvienko, D; Miyabayashi, K; Miyata, H; Mizuk, R; Moll, A; Muramatsu, N; Nakano, E; Nakao, M; Natkaniec, Z; Nayak, M; Nedelkovska, E; Ng, C; Nellikunnummel, N; Nitoh, O; Ogawa, A; Ogawa, S; Ohshima, T; Okuno, S; Olsen, S L; Oswald, C; Pakhlov, P; Park, H; Park, H K; Pedlar, T K; Pestotnik, R; Petrič, M; Piilonen, L E; Röhrken, M; Sahoo, H; Sakai, Y; Sandilya, S; Santelj, L; Sanuki, T; Sato, Y; Schneider, O; Schnell, G; Schwanda, C; Senyo, K; Seon, O; Sevior, M E; Shapkin, M; Shen, C P; Shibata, T -A; Shiu, J -G; Shwartz, B; Sibidanov, A; Simon, F; Smerkol, P; Sohn, Y -S; Sokolov, A; Solovieva, E; Starič, M; Sumihama, M; Sumiyoshi, T; Tatishvili, G; Teramoto, Y; Tsuboyama, T; Uchida, M; Uglov, T; Unno, Y; Uno, S; Usov, Y; Van Hulse, C; Varner, G; Vorobyev, V; Wagner, M N; Wang, C H; Wang, J; Wang, M -Z; Wang, P; Watanabe, M; Watanabe, Y; Williams, K M; Won, E; Yamashita, Y; Zhilich, V; Zhulanov, V

    2013-01-01

    Precise measurements of inclusive multiplicities of charged pions and kaons produced in electron-positron annihilation have been carried out at a center-of-mass energy of 10.52 GeV. The measurements were performed with the Belle detector at the KEKB electron-positron collider using a data sample containing 113 million e+e- -> qqbar events, where q={u,d,s,c}. We present charge-integrated multiplicities 1/N_evts * dN_h+-/dz for h+- = pi+-, K+- as a function of the relative hadron energy z = 2*E_h / sqrt{s} from 0.2 to 0.98 (0.97) for pions (kaons). The combined statistical and systematic uncertainties for pi+- (K+-) are 4% (5%) at z ~ 0.6 and 18% (51%) at z ~ 0.9. The multiplicities are the first measurements of the z-dependence of pion and kaon multiplicities for z > 0.7 as well as the first precision multiplicity measurements at a center-of-mass energy far below the Z^0 resonance used by the experiments at LEP and SLC.

  19. Observation of Electron Cloud Instabilities and Emittance Dilution at the Cornell Electron-Positron Storage Ring Test Accelerator

    International Nuclear Information System (INIS)

    Electron cloud related emittance dilution and instabilities of bunch trains limit the performance of high intensity circular colliders. One of the key goals of the Cornell electron-positron storage ring Test Accelerator (CesrTA) research program is to improve our understanding of how the electron cloud alters the dynamics of bunches within the train. Single bunch beam diagnotics have been developed to measure the beam spectra, vertical beam size, two important dynamical effects of beams interacting with the electron cloud, for bunch trains on a turn-by-turn basis. Experiments have been performed at CesrTA to probe the interaction of the electron cloud with stored positron bunch trains. The purpose of these experiments was to characterize the dependence of beam-electron cloud interactions on the machine parameters such as bunch spacing, vertical chromaticity, and bunch current. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated beam position monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains; 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches in a train under many different operational conditions

  20. Observation of Electron Cloud Instabilities and Emittance Dilution at the Cornell Electron-Positron Storage Ring Test Accelerator

    Science.gov (United States)

    Holtzapple, R. L.; Billing, M. G.; Campbell, R. C.; Dugan, G. F.; Flanagan, J.; McArdle, K. E.; Miller, M. I.; Palmer, M. A.; Ramirez, G. A.; Sonnad, K. G.; Totten, M. M.; Tucker, S. L.; Williams, H. A.

    2016-04-01

    Electron cloud related emittance dilution and instabilities of bunch trains limit the performance of high intensity circular colliders. One of the key goals of the Cornell electron-positron storage ring Test Accelerator (CesrTA) research program is to improve our understanding of how the electron cloud alters the dynamics of bunches within the train. Single bunch beam diagnotics have been developed to measure the beam spectra, vertical beam size, two important dynamical effects of beams interacting with the electron cloud, for bunch trains on a turn-by-turn basis. Experiments have been performed at CesrTA to probe the interaction of the electron cloud with stored positron bunch trains. The purpose of these experiments was to characterize the dependence of beam-electron cloud interactions on the machine parameters such as bunch spacing, vertical chromaticity, and bunch current. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated beam position monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains; 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches in a train under many different operational conditions.

  1. Crab Waist collision scheme: a novel approach for particle colliders

    CERN Document Server

    Zobov, Mikhail

    2016-01-01

    A new concept of nonlinear focusing of colliding bunches, called Crab Waist (CW)collision scheme, has been proposed at LNF INFN. It has been successfully tested at the Italian lepton collider DAFNE in operational conditions providing luminosity for two different experimental detectors, SIDDHARTA and KLOE-2. Considering a high efficiency of the scheme for increasing collision luminosity and its relative simplicity for implementation several new collider projects have been proposed and are under development at present. These are the SuperKEKB B-factory ready to start commissioning in 2016 in Japan, the SuperC-Tau factory proposed in Novosibirsk and entered in the short list of Russian mega-science projects, the new 100-km electron-positron Future Circular Collider (FCC-ee) under design study at CERN and some others. In this paper we describe the CW collision scheme, discuss its advantages and report principal results achieved at the electron-positron Phi-factory DAFNE.

  2. Future colliders based on a modulated proton bunch driven plasma wakefield acceleration

    CERN Document Server

    Xia, Guoxing; Muggli, Patric

    2012-01-01

    Recent simulation shows that a self-modulated high energy proton bunch can excite a large amplitude plasma wakefield and accelerate an externally injected electron bunch to the energy frontier in a single stage acceleration through a long plasma channel. Based on this scheme, future colliders, either an electron-positron linear collider (e+-e- collider) or an electron-hadron collider (e-p collider) can be conceived. In this paper, we discuss some key design issues for an e+-e- collider and a high energy e-p collider, based on the existing infrastructure of the CERN accelerator complex.

  3. Bound-free pair production cross section in heavy-ion colliders from the equivalent photon approach

    CERN Document Server

    Aste, Andreas

    2007-01-01

    Exact calculations of the electron-positron pair production by a single photon in the Coulomb field of a nucleus with simultaneous capture of the electron into the K-shell are discussed for the nuclear charges Z=29 and Z=92. Using the equivalent photon method of Weizsaecker and Williams, a simple expression for the bound-free production of electron-positron pairs by colliding very-high-energy fully stripped heavy ions is derived for arbitrary nuclear charges.

  4. Laser-plasma-based linear collider using hollow plasma channels

    Science.gov (United States)

    Schroeder, C. B.; Benedetti, C.; Esarey, E.; Leemans, W. P.

    2016-09-01

    A linear electron-positron collider based on laser-plasma accelerators using hollow plasma channels is considered. Laser propagation and energy depletion in the hollow channel is discussed, as well as the overall efficiency of the laser-plasma accelerator. Example parameters are presented for a 1-TeV and 3-TeV center-of-mass collider based on laser-plasma accelerators.

  5. Klystron switching power supplies for the Internation Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    Fraioli, Andrea; /Cassino U. /INFN, Pisa

    2009-12-01

    The International Linear Collider is a majestic High Energy Physics particle accelerator that will give physicists a new cosmic doorway to explore energy regimes beyond the reach of today's accelerators. ILC will complement the Large Hadron Collider (LHC), a proton-proton collider at the European Center for Nuclear Research (CERN) in Geneva, Switzerland, by producing electron-positron collisions at center of mass energy of about 500 GeV. In particular, the subject of this dissertation is the R&D for a solid state Marx Modulator and relative switching power supply for the International Linear Collider Main LINAC Radio Frequency stations.

  6. Muon colliders, frictional cooling and universal extra dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Greenwald, Daniel E.

    2011-07-20

    A muon collider combines the advantages of proton-proton and electron-positron colliders, sidestepping many of their disadvantages, and has the potential to make discoveries and precision measurements at high energies. However, muons bring their own technical challenges, largely relating to their instability. We present a summary of the motivations and R and D efforts for a muon collider. We detail a scheme for preparing high-luminosity muon beams on timescales shorter than the muon lifetime, and an experiment to demonstrate aspects of this scheme at the Max Planck Institute for Physics. We also investigate the potentials to discover physics beyond the standard model at a muon collider. (orig.)

  7. Muon colliders, frictional cooling and universal extra dimensions

    International Nuclear Information System (INIS)

    A muon collider combines the advantages of proton-proton and electron-positron colliders, sidestepping many of their disadvantages, and has the potential to make discoveries and precision measurements at high energies. However, muons bring their own technical challenges, largely relating to their instability. We present a summary of the motivations and R and D efforts for a muon collider. We detail a scheme for preparing high-luminosity muon beams on timescales shorter than the muon lifetime, and an experiment to demonstrate aspects of this scheme at the Max Planck Institute for Physics. We also investigate the potentials to discover physics beyond the standard model at a muon collider. (orig.)

  8. Charged Particles Multiplicity and Scaling Violation of Fragmentation Functions in Electron-Positron Annihilation

    CERN Document Server

    Ghaffary, Tooraj

    2016-01-01

    In electron positron annihilation, changing quarks into the final hadron states is being described by fragmentation function. Based on the scaling hypothesis, this function will be independent from the center of mass energy. Gluon radiation violates the scaling feature. Transverse momentum distribution plays an important role in scaling violation of fragmentation functions. In this article, by the use of data resulted from the annihilation process of electron positron in AMY detector at 60 GeV center of mass energy, first, charged particles multiplicity distribution will be obtained and it will be fitted with the KNO scaling. Furthermore, momentum spectra of charged particles and momentum distribution respect to the jet axis will be obtained. Then, the results will be compared regarding the different models of QCD; as well, the distribution of fragmentation functions and scaling violations will be studied. It is being expected that the scaling violations of the fragmentation functions of gluon jet are stronge...

  9. Electroweak interactions between intense neutrino beams and dense electron-positron magneto-plasmas

    CERN Document Server

    Tsintsadze, N L; Stenflo, L

    2003-01-01

    The electroweak coupling between intense neutrino beams and strongly degenerate relativistic dense electron-positron magneto-plasmas is considered. The intense neutrino bursts interact with the plasma due to the weak Fermi interaction force, and their dynamics is governed by a kinetic equation. Our objective here is to develop a kinetic equation for a degenerate neutrino gas and to use that equation to derive relativistic magnetohydrodynamic equations. The latter are useful for studying numerous collective processes when intense neutrino beams nonlinearly interact with degenerate, relativistic, dense electron-positron plasmas in strong magnetic fields. If the number densities of the plasma particles are of the order of 10 sup 3 sup 3 cm sup - sup 3 , the pair plasma becomes ultra-relativistic, which strongly affects the potential energy of the weak Fermi interaction. The new system of equations allows several neutrino-driven streaming instabilities involving new types of relativistic Alfven-like waves, The re...

  10. Nonlinear interaction of photons and phonons in electron-positron plasmas

    International Nuclear Information System (INIS)

    Nonlinear interaction of electromagnetic waves and acoustic modes in an electron-positron plasma is investigated. The plasma of electrons and positrons is quite plastic so that the imposition of electromagnetic (EM) waves causes depression of the plasma and other structural imprints on it through either the nonresonant or resonant interaction. Our theory shows that the nonresonant interaction can lead to the coalescence of photons and collapse of plasma cavity in higher (≥ 2) dimensions. The resonant interaction, in which the group velocity of EM waves is equal to the phase velocity of acoustic waves, is analyzed and a set of basic equations of the system is derived via the reductive perturbation theory. We find new solutions of solitary types: bright solitons, kink solitons, and dark solitons as the solutions to these equations. Our computation hints their stability. An impact of the present theory on astrophysical plasma settings is expected, including the cosmological relativistically hot electron-positron plasma. 20 refs., 9 figs

  11. Hadronic cross sections in electron-positron annihilation with tagged photon

    International Nuclear Information System (INIS)

    We consider events with tagged photons in the process of electron-positron annihilation into hadrons. We propose to use the initial state radiation at meson factories to scan with the energy the hadronic cross section. QED radiative corrections are taken into account and the corresponding results for the total and partial cross sections are given in analytic form. Some numerical estimates are also given

  12. open-quotes Heavy light bulletsclose quotes in electron-positron plasma

    International Nuclear Information System (INIS)

    The nonlinear propagation of circularly polarized electromagnetic waves with relativistically strong amplitudes in an unmagnetized hot electron-positron plasma with a small fraction of ions is investigated. The possibility of finding localized solutions in such a plasma is explored. It is shown that these plasmas support the propagation of open-quotes heavy light bulletsclose quotes; nondiffracting and nondispersive electromagnetic (EM) pulses with large density bunching

  13. Three dimensional electron-positron momentum density in V, Nb and Ta

    International Nuclear Information System (INIS)

    The three dimensional electron-positron momentum density in V, Nb and Ta has been reconstructed from measurements of two dimensional angular correlation of positron annihilation radiations (2D-ACAR) followed by the image reconstruction technique based on a direct Fourier transformation. We determined the position of Fermi surface sheets; Γ-centered hole octahedron, multiply connected jungle-gym arms and N-centered hole ellipsoids. The Fermi surface topology is in good agreement with the theory

  14. {open_quotes}Heavy light bullets{close_quotes} in electron-positron plasma

    Energy Technology Data Exchange (ETDEWEB)

    Berezhiani, V.I. [International Centre for Theoretical Physics, Trieste (Italy); Mahajan, S.M. [Univ. of Texas, Austin, TX (United States). Institute for Fusion Studies

    1995-03-01

    The nonlinear propagation of circularly polarized electromagnetic waves with relativistically strong amplitudes in an unmagnetized hot electron-positron plasma with a small fraction of ions is investigated. The possibility of finding localized solutions in such a plasma is explored. It is shown that these plasmas support the propagation of {open_quotes}heavy light bullets{close_quotes}; nondiffracting and nondispersive electromagnetic (EM) pulses with large density bunching.

  15. Causal approach for the electron-positron scattering in Generalized Quantum Electrodynamics

    OpenAIRE

    Bufalo, R.; Pimentel, B. M.; Soto, D. E.

    2014-01-01

    In this paper we study the generalized electrodynamics contribution for the electron-positron scattering process, $e^{-}e^{+}\\rightarrow e^{-}e^{+}$, the Bhabha scattering. Within the framework of the standard model, for energies larger when compared to the electron mass, we calculate the cross section expression for the scattering process. This quantity is usually calculated in the framework of the Maxwell electrodynamics and, by phenomenological reasons, corrected by a cut-off parameter. On...

  16. Large amplitude localized structures in a relativistic electron-positron ion plasma

    International Nuclear Information System (INIS)

    The nonlinear propagation of circularly polarized electromagnetic (CPEM) waves with relativistic strong amplitude in an unmagnetized cold electron-positron ion plasma is investigated. The possibility of finding soliton solutions in such a plasma is explored. In one- and two-dimensions it is shown that the presence of a small fraction of massive ions in the plasma lead to stable localized solutions. (author). 15 refs, 5 figs

  17. Calculation of Higher Order Effects in Electron-Positron Pair Production in Relativistic Heavy Ion Collisions

    OpenAIRE

    Hencken, Kai; Trautmann, Dirk; Baur, Gerhard

    1998-01-01

    We present a calculation of higher order effects for the impact parameter dependent probability for single and multiple electron-positron pairs in (peripheral) relativistic heavy ion collisions. Also total cross sections are given for SPS and RHIC energies. We make use of the expression derived recently by several groups where the summation of all higher orders can be done analytically in the high energy limit. An astonishing result is that the cross section, that is, integrating over all imp...

  18. Electron/positron measurements obtained with the Mars Science Laboratory Radiation Assessment Detector on the surface of Mars

    International Nuclear Information System (INIS)

    The Radiation Assessment Detector (RAD), on board the Mars Science Laboratory (MSL) rover Curiosity, measures the energetic charged and neutral particles and the radiation dose rate on the surface of Mars. Although charged and neutral particle spectra have been investigated in detail, the electron and positron spectra have not been investigated yet. The reason for that is that they are difficult to separate from each other and because of the technical challenges involved in extracting energy spectra from the raw data. We use GEANT4 to model the behavior of the RAD instrument for electron/positron measurements.We compare Planetocosmics predictions for different atmospheric pressures and different modulation parameters Φ with the obtained RAD electron/positron measurements.We find that the RAD electron/positron measurements agree well with the spectra predicted by Planetocosmics. Both RAD measurements and Planetocosmics simulation show a dependence of the electron/positron fluxes on both atmospheric pressure and solar modulation potential.

  19. Electron/positron measurements obtained with the Mars Science Laboratory Radiation Assessment Detector on the surface of Mars

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, J.; Wimmer-Schweingruber, R.F.; Appel, J. [Kiel Univ. (Germany). Inst. of Experimental and Applied Physics; and others

    2016-04-01

    The Radiation Assessment Detector (RAD), on board the Mars Science Laboratory (MSL) rover Curiosity, measures the energetic charged and neutral particles and the radiation dose rate on the surface of Mars. Although charged and neutral particle spectra have been investigated in detail, the electron and positron spectra have not been investigated yet. The reason for that is that they are difficult to separate from each other and because of the technical challenges involved in extracting energy spectra from the raw data. We use GEANT4 to model the behavior of the RAD instrument for electron/positron measurements.We compare Planetocosmics predictions for different atmospheric pressures and different modulation parameters Φ with the obtained RAD electron/positron measurements.We find that the RAD electron/positron measurements agree well with the spectra predicted by Planetocosmics. Both RAD measurements and Planetocosmics simulation show a dependence of the electron/positron fluxes on both atmospheric pressure and solar modulation potential.

  20. Physics at Future Circular Colliders

    Science.gov (United States)

    Kotwal, Ashutosh

    2016-03-01

    The Large Hadron Collider has been a grand success with the discovery of the Higgs boson, with bright prospects for additional discoveries since the recent increase in collider energy and the anticipated large datasets. Big open questions such as the nature of dark matter, the origin of the matter-antimatter asymmetry in the Universe, and the theoretical puzzle of the finely-tuned parameters in the Higgs sector, demand new physics principles that extend the established Standard Model paradigm. Future circular colliders in a substantially larger tunnel can house both a high luminosity electron-positron collider for precision measurements of Higgs and electroweak parameters, as well as a very high energy proton-proton collider which can directly manifest particles associated with these new physics principles. We discuss the physics goals of these future circular colliders, and the prospects for elucidating fundamental new laws of nature that will significantly extend our understanding of the Universe. Detailed studies of the discovery potential in specific benchmark models will be presented, with implications for detector design.

  1. Hunting Radions at Linear Colliders

    CERN Document Server

    Datta, A; Datta, Anindya; Huitu, Katri

    2004-01-01

    We investigate the possibility to disentangle the radions in the Randall-Sundrum scenario from higgs boson at the next generation high energy $e^+ e^-$ linear colliders. Due to trace anomaly, the radion coupling (and in turn the branching ratio) to gluons is enhanced over the same for the Standard Model (SM) higgs. We study the radion production at electron-positron colliders, via the fusion of W-bosons in association with neutrinos, and propose to investigate radion decay to a pair of gluons. At 500 GeV center of mass energy, our signal is not very promising. We find our results are encouraging for finding radion and differentiating it from higgs for center of mass energies of 1 TeV and above.

  2. Static Electron-Positron Pair Creation in Strong Fields for a Nonlinear Dirac model

    CERN Document Server

    Sabin, Julien

    2011-01-01

    We consider the Hartree-Fock approximation of Quantum Electrodynamics, with the exchange term neglected. We prove that the probability of static electron-positron pair creation for the Dirac vacuum polarized by an external field of strength $Z$ behaves as $1-\\exp(-\\kappa Z^{2/3})$ for $Z$ large enough. Our method involves two steps. First we estimate the vacuum expectation of general quasi-free states in terms of their total number of particles, which can be of general interest. Then we study the asymptotics of the Hartree-Fock energy when $Z\\to+\\infty$ which gives the expected bounds.

  3. Electron-positron pair production in space-time varying external electric fields

    CERN Document Server

    Aleksandrov, I A; Shabaev, V M

    2016-01-01

    The Schwinger mechanism of the electron-positron pair production in the presence of strong external electric fields is analyzed numerically for the case of one- and two-dimensional field configurations where the external field depends both on time and one spatial coordinate. In order to provide this analysis, a new efficient numerical approach was developed. The number of particles created is obtained numerically and also compared with the analytical results for several exactly solvable one-dimensional backgrounds. For the case of two-dimensional field configurations a few generic properties of pair-creation process are found. The method employed is described in detail.

  4. Importance of non-local electron-positron correlations for positron annihilation characteristics in solids

    Energy Technology Data Exchange (ETDEWEB)

    Rubaszek, A. [Polska Akademia Nauk, Wroclaw (Poland). Inst. Niskich Temperatur i Badan Strukturalnych; Szotek, Z.; Temmerman, W.M. [Daresbury Lab., Warrington (United Kingdom)

    2001-07-01

    Several methods to describe the electron-positron (e-p) correlation effects are used in calculations of positron annihilation characteristics in solids. The weighted density approximation (WDA), giving rise to the non-local, state-selective e-p correlation functions, is applied to calculate positron annihilation rates and e-p momentum densities in a variety of metals and silicon. The WDA results are compared to the results of other methods such as the independent particle model, local density approximation, generalised gradient approximation, and also to experiments. The importance of non-locality and state-dependence of the e-p correlation functions is discussed. (orig.)

  5. Coherent combs of anti-matter from nonlinear electron-positron pair creation

    CERN Document Server

    Krajewska, K

    2014-01-01

    Electron-positron pair creation in collisions of a modulated laser pulse with a high-energy photon (nonlinear Breit-Wheeler process) is studied by means of strong-field quantum electrodynamics. It is shown that the driving pulse modulations lead to appearance of comb structures in the energy spectra of produced positrons (electrons). It is demonstrated that these combs result from a coherent enhancement of probability amplitudes of pair creation from different modulations of the laser pulse. Thus, resembling the Young-double slit experiment for anti-matter (matter) waves.

  6. Coherent combs of antimatter from nonlinear electron-positron-pair creation

    Science.gov (United States)

    Krajewska, K.; Kamiński, J. Z.

    2014-11-01

    Electron-positron-pair creation in collisions of a modulated laser pulse with a high-energy photon (nonlinear Breit-Wheeler process) is studied by means of strong-field quantum electrodynamics. It is shown that the driving pulse modulations lead to the appearance of comb structures in the energy spectra of produced positrons (electrons). It is demonstrated that these combs result from a coherent enhancement of probability amplitudes of pair creation from different modulations of the laser pulse, thus resembling the Young-type double-slit experiment for antimatter (matter) waves.

  7. On the electron-positron energy asymmetry in K_L --> pi0 e+ e-

    OpenAIRE

    Gao, Dao-Neng

    2003-01-01

    Motivated by some new experimental and theoretical efforts, we update the theoretical analysis of the electron-positron energy asymmetry, which arises, in K_L --> pi0 e+ e-, from the two-photon intermediate state in the standard model. It is found that the measurement of this asymmetry in future experiments may increase our understanding of the K_{L, S} --> pi0 e+ e- decays, which would thus provide some useful information on quark flavor physics. Meanwhile, in the standard model the electron...

  8. Final-state Interaction Effects on Inclusive Two-particle Production in Electron-positron Annihilation

    CERN Document Server

    Yang Jian Jun; Yang, Jian-Jun; Lu, Wei

    1997-01-01

    The final-state interaction effects on the inclusive two-particle production in electron-positron annihilation are investigated within the context of the one-photon annihilation approximation. Such effects are characterized by one structure function in the decomposition of the hadronic tensor. On the basis of the positivity, we derived an inequality to bound this structure function. The price to access it experimentally is to polarize longitudinally one of the initial-state beam, to say, the electron beam, and measure the corresponding single spin asymmetry. By combining the Callan-Gross relation with our positivity analysis, we obtain an upper bound for the single spin asymmetry considered.

  9. Electrostatic Nonlinear Structures in Dissipative Electron-Positron-Ion Quantum Plasmas

    Institute of Scientific and Technical Information of China (English)

    S. A. Khan; Q. Haque

    2008-01-01

    @@ Low frequency (in comparison to ion plasma frequency) ion-acoustic shocks and solitons in superdense electron-positron-ion quantum plasmas are studied.The quantum hydrodynamic model is used incorporating quantum Bohm forces and Fermi-Dirac statistical corrections to derive the deformed Korteweg de Vries-Burgers (dKdVB) equation in weakly nonlinear limit.The travelling wave solution of dKdVB equation is presented and results are discussed in different limits.It is found that shock height increases with increase of quantum pressure, positron concentration and dissipation.Further, it is seen that the width of soliton decreases with increase of quantum pressure.

  10. Low frequency solitary waves in magnetized electron-positron-ion plasmas

    International Nuclear Information System (INIS)

    Nonlinear electrostatic and electromagnetic low frequency waves are studied in magnetized electron-positron-ion (EPI) plasmas. The effects of full nonlinearity and three dimensional ion motion have been taken into account. It is shown that both density dips and humps can coexist in EPI plasmas along with bell-shaped and kink-type solitons. The new results as well as several limiting cases for comparison with earlier work have been discussed, for the sake of completeness. Relevance of this work to space, astrophysical and laboratory plasmas is pointed out. (author)

  11. R-ratio of electron-positron annihilation into hadrons: higher-order pi2-terms

    CERN Document Server

    Nesterenko, A V

    2016-01-01

    High-energy behavior of R-ratio of electron-positron annihilation into hadrons is studied. In particular, it is argued that at any given order of perturbation theory the re-expansion of the R-ratio in the ultraviolet asymptotic can be reduced to the form of power series in the naive continuation of the strong running coupling into the timelike domain. The convergence range of the re-expanded R-ratio and the corresponding higher-order pi2-terms are discussed.

  12. QCD corrections to semi-inclusive hadron production in electron-positron annihilation at two loops

    Energy Technology Data Exchange (ETDEWEB)

    Mitov, A.; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2006-04-15

    We report on the analytic calculation of the second-order QCD corrections to semi-inclusive hadron production in electron-positron annihilation. The calculation of the single-particle inclusive cross-section in time-like kinematics is performed in Mellin N-space and uses an algorithmic evaluation of inclusive phase-space integrals, based on the unitarity cutting rules and integration-by-parts. We obtain splitting functions and coefficient functions up to second order in the strong coupling {alpha}{sub s}. Our results are in agreement with earlier calculations in the literature by Rijken and van Neerven. (Orig.)

  13. Nonplanar Ion-Acoustic Solitons in Electron-Positron-Ion Quantum Plasmas

    Institute of Scientific and Technical Information of China (English)

    S. A. Khan; S. Mahmood; Arshad M. Mirza

    2009-01-01

    @@ The propagation of nonplanar quantum ion-acoustic solitary waves in a dense, unmagnetized electron-positron-ion (e-p-i) plasma are studied by using the Korteweg-de Vries (KdV) model The quantum hydrodynamic (QHD) equations are used taking into account the quantum diffraction and quantum statistics corrections. The analytical and numerical solutions of KdV equation reveal that the nonplanar ion-acoustic solitons are modified significantly with quantum corrections and positron concentration, and behave differently in different geometries.

  14. Ion-acoustic envelope excitations in electron-positron-ion plasma with nonthermal electrons

    Energy Technology Data Exchange (ETDEWEB)

    Gill, Tarsem Singh, E-mail: gillsema@yahoo.co.i [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Bains, Amandeep Singh [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Saini, Nareshpal Singh, E-mail: nssaini@yahoo.co [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Center for Plasma Physics, Department of Physics and Astronomy, Queen' s University Belfast, BT7 1NN (United Kingdom); Bedi, Chanchal [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India)

    2010-07-12

    A theoretical investigation has been made for modulational instability of ion-acoustic waves in an electron-positron-ion plasma with nonthermal electrons. Employing reductive perturbation method (RPM), the nonlinear Schroedinger equation (NLSE) is derived. The dispersive and nonlinearity coefficients, P and Q, respectively, are the functions of nonthermal parameter ({beta}), ratio of positron to electron density (d), ratio of the electron to positron temperature ({delta}) and ratio of ion to electron temperature ({sigma}). It is observed that these parameters significantly modify the conditions of the modulational instability. The system supports both types of bright and dark envelope excitations.

  15. Search for magnetic monopoles in electron-positron collisions at 34 GeV CM energy

    International Nuclear Information System (INIS)

    A search for heavily ionizing particles was carried out at the electron-positron storage ring PETRA with the help of Kapton detectors placed inside the vacuum pipe. The total integrated luminosity was 90 pb-1 at CM energies above 34 GeV. The search was sensitive to particles with magnetic charge from 1 x (137/2)e to 5 x (137/2)e and with masses up to 10-16 GeV/c2. No such particle was found, leading to an upper limit of the production cross section of monopole-antimonopole pairs of 4 x 10-38 cm2 (95% CL). (orig.)

  16. QCD corrections to semi-inclusive hadron production in electron-positron annihilation at two loops

    International Nuclear Information System (INIS)

    We report on the analytic calculation of the second-order QCD corrections to semi-inclusive hadron production in electron-positron annihilation. The calculation of the single-particle inclusive cross-section in time-like kinematics is performed in Mellin N-space and uses an algorithmic evaluation of inclusive phase-space integrals, based on the unitarity cutting rules and integration-by-parts. We obtain splitting functions and coefficient functions up to second order in the strong coupling αs. Our results are in agreement with earlier calculations in the literature by Rijken and van Neerven. (Orig.)

  17. Concept for a Future Super Proton-Proton Collider

    CERN Document Server

    Tang, Jingyu; Chai, Weiping; Chen, Fusan; Chen, Nian; Chou, Weiren; Dong, Haiyi; Gao, Jie; Han, Tao; Leng, Yongbin; Li, Guangrui; Gupta, Ramesh; Li, Peng; Li, Zhihui; Liu, Baiqi; Liu, Yudong; Lou, Xinchou; Luo, Qing; Malamud, Ernie; Mao, Lijun; Palmer, Robert B; Peng, Quanling; Peng, Yuemei; Ruan, Manqi; Sabbi, GianLuca; Su, Feng; Su, Shufang; Stratakis, Diktys; Sun, Baogeng; Wang, Meifen; Wang, Jie; Wang, Liantao; Wang, Xiangqi; Wang, Yifang; Wang, Yong; Xiao, Ming; Xing, Qingzhi; Xu, Qingjin; Xu, Hongliang; Xu, Wei; Witte, Holger; Yan, Yingbing; Yang, Yongliang; Yang, Jiancheng; Yuan, Youjin; Zhang, Bo; Zhang, Yuhong; Zheng, Shuxin; Zhu, Kun; Zhu, Zian; Zou, Ye

    2015-01-01

    Following the discovery of the Higgs boson at LHC, new large colliders are being studied by the international high-energy community to explore Higgs physics in detail and new physics beyond the Standard Model. In China, a two-stage circular collider project CEPC-SPPC is proposed, with the first stage CEPC (Circular Electron Positron Collier, a so-called Higgs factory) focused on Higgs physics, and the second stage SPPC (Super Proton-Proton Collider) focused on new physics beyond the Standard Model. This paper discusses this second stage.

  18. At work on LEP, the world’s most powerful electron–positron collider

    CERN Multimedia

    Patrice Loiez,

    1999-01-01

    The LHC will be built inside the same tunnel as an existing accelerator, the Large Electron Positron (LEP) collider which came on stream in 1989. LEP will be removed from the tunnel at the end of this year to make way for the LHC. Here technicians make delicate adjustments to one of LEP’s thousands of magnets.

  19. General formulae of luminosity for various types of colliding beam machines

    International Nuclear Information System (INIS)

    Summarized are the formulae of luminosity for proton-proton, electron-positron and electron-proton colliding beam machines. Both coasting and bunched proton beams are considered. The expressions are derived from the first principle. These formulae will be useful for the design of an intersecting storage accelerator such as TRISTAN. (auth.)

  20. Beijing Alley

    Institute of Scientific and Technical Information of China (English)

    LiXiaoke

    2004-01-01

    There are many distinguished artists with work in residence at Beijing's Creation Gallery, but there is one worthy of particular mention - gallery founder Li Xiaoke. Through his work, Li successfully unites elements of western art with traditional Chinese ideas and art theories. His favorite places of inspiration are old Beijing, Tibet, and southern China.

  1. Opportunities with top quarks at future circular colliders

    CERN Document Server

    Fuks, Benjamin

    2014-01-01

    We describe various studies relevant for top physics at future circular collider projects currently under discussion. We show how highly-massive top-antitop systems produced in proton-proton collisions at a center-of-mass energy of 100 TeV could be observed and employed for constraining top dipole moments, investigate the reach of future proton-proton and electron-positron machines to top flavor-changing neutral interactions, and discuss top parton densities.

  2. Top Production and Decay at Linear Colliders: QCD Corrections

    OpenAIRE

    Macesanu, Cosmin; Orr, Lynne H.

    2000-01-01

    We present the results of an exact calculation of gluon radiation in top production and decay at high energy electron-positron colliders. We include all spin correlations and interferences, the bottom quark mass, and finite top width effects in the matrix element calculation. We study properties of the radiated gluons and implications for top mass measurement. We also discuss virtual corrections to the process.

  3. Of Linear Colliders, the GDE Workshop at Bangalore, Mughals, Camels, Elephants and Sundials

    International Nuclear Information System (INIS)

    In this colloquium, the speaker will give a summary of the recent International Linear Collider (ILC) Global Design Effort (GDE) Workshop at Bangalore and how the High Energy Physics community converged to this meeting after many years of electron-positron linear collider design and experimental work. Given that this workshop for the first time took place in India, the speaker will also show a few pictures and talk briefly about what he learned in that fascinating country.

  4. Concluding talk-seminar on critical issues in development of new linear colliders

    International Nuclear Information System (INIS)

    The growth of particle colliders is summarized, with their collision energy in the frame of the elementary constituents given for numerous specific machines. The logic concerning the design of electron-positron colliders and definition of parameters are briefly discussed. Several issues are covered which are presently uncertain, including beamstrahlung and interaction among beams of transverse dimensions in the angstrom range. Alternate power sources and their economy are considered as well as superconducting structures

  5. Comparison of backgrounds in detectors for LHC, NLC and μ+μ- colliders

    International Nuclear Information System (INIS)

    Background levels in detectors at future high-luminosity colliders of three different types - proton-proton, electron-positron, and muon- antimuon - are analyzed. Two sources - debris from the collision points and those from an accelerator tunnel - are studied. It is shown that hadron, electron and muon colliders are similar and very different at the same time with respect to background origin, integrated radiation levels and instantaneous rates of particles in the detectors. 23 refs., 11 figs., 4 tabs

  6. Study of $\\Delta(1232)$ isobar electroproduction at VEPP-2M $e^+e^-$ collider

    OpenAIRE

    Achasov, M. N.; Bozhenok, A. V.; Bukin, A.D.; Bukin, D. A.; Burdin, S. V.; Dimova, T. V.; Dolinsky, S. I.; Druzhinin, V. P.; Dubrovin, M. S.; Gaponenko, I. A.; Golubev, V. B.; Ivanchenko, V. N.(Budker Institute of Nuclear Physics SB RAS, 630090, Novosibirsk, Russia); Korol, A.A.; Koshuba, S. V.; Lysenko, A. P.

    1998-01-01

    Results from the Spherical Nonmagnetic Detector (SND) on $\\Delta (1232)$ isobar electroproduction in the collisions of beam electrons (positrons) and residual gas nuclei in the VEPP-2M $e^+e^-$ collider are presented. On the basis of the obtained data the expected counting rate of this process in future high luminosity $e^+e^-$ colliders (~$\\phi$-, $c$-$\\tau$- and $b$-factories) was estimated.

  7. Preliminary Report on the Evaluation of an Electron-Positron Collider as a source of Monoenergetic Photons

    Energy Technology Data Exchange (ETDEWEB)

    Fast, James E.; Campbell, Luke W.

    2009-11-30

    Abstract Active interrogation methods are being investigated to detect shielded special nuclear material (SNM). These approaches utilize either neutron or photon beams to excite the SNM in concert with either neutron or gamma ray detectors to observe the stimulated emissions. The two primary methodologies with photon beams are photofission and nuclear resonance florescence (NRF). Photofission requires photons energies of 7-10 MeV while NRF requires photon energies around 2 MeV. For both techniques, photons that are not in the appropriate energy band, e.g. the low energy tail of a Bremsstrahlung photon beam, contribute unwanted additional radiation dose to cargo. Typically less than 10% of the photons are in the usable energy band. The additional photon production generates a commensurate amount of additional radiation dose in the source and target areas, impacting shielding requirements and/or dose to operators and equipment and at the expense of a similar increase in power consumption. Hence it is highly desirable to produce narrow energy (“monoenergetic”) photon beams with tunable energy in the range of ~2-20 MeV.

  8. VEPP-2M new electron-positron colliding beam facility of the Siberian Institute of Nuclear Physics

    International Nuclear Information System (INIS)

    A description and results of constructing the 670 MeV VEPP-2M strong-focusing storage ring are given. The VEPP-2 is a booster where electron and positron beams are accumulated in succession and then extracted into the VEPP-2M. The VEPP-2M comprises light sections of a magentic system, four short gaps and four long ones. Three gaps, each of 650 mm long, are intended to conduct experiments on high energy physics. Present status of the VEPP-2M of 1972 is described and the program of experiments planned is presented

  9. Hydrodynamics of an electron-positron plasma near a black hole: Applications to jet formation

    International Nuclear Information System (INIS)

    We investigate some features of the hydrodynamics and neutrino physics in the (predominantly) electron-positron plasma above a hyperaccreting disk (or torus) around a black hole, a conjectured engine for a short gamma ray burst. We suggest a possible scenario in which plasma in the region very near the black hole, energetically driven by neutrino annihilation, emerges as a subsonic wind, which in a spherically symmetrical case would decelerate as it moves out. In this case we argue that the plasma heating will be primarily through neutrino-electron and neutrino-positron scattering, and that this process will be important throughout a region considerably larger than that of the neutrino annihilation process. In simple solutions a relatively gentle anisotropy in the heating through this process can create an approximately conical sonic surface, aligned with the system's axis. Inside this cone the fluid accelerates upwards as in standard jet models

  10. Electromagnetic envelope solitons in ultrarelativistic inhomogeneous electron-positron-ion plasma

    International Nuclear Information System (INIS)

    The nonlinear interaction of ultra-intense short laser beam and homogeneous/inhomogeneous electron-positron-ion (e-p-i) plasma is investigated. It is found that soliton solutions can exist in both homogeneous and inhomogeneous e-p-i plasma. The influence of the positron density, the phase velocity, the inhomogeneity nature, and the Hamiltonian of the system on the soliton structure is investigated. The evolution of envelope solitons in homogeneous e-p-i plasma is analyzed analytically by using a two-time-scale method and confirmed by numerical simulations. However, the soliton solutions can exist in inhomogeneous e-p-i plasma only when the positron density is high enough. Furthermore, the phase diagram for existing envelope soliton in positron density and phase velocity of the wave plane is obtained

  11. Oscillating two-stream instability in a magnetized electron-positron-ion plasma

    Science.gov (United States)

    Tinakiche, Nouara; Annou, R.

    2015-04-01

    Oscillating two-stream instability (OTSI) in a magnetized electron-ion plasma has been thoroughly studied, e.g., in ionospheric heating experiments [C. S. Liu and V. K. Tripathi, Interaction of Electromagnetic Waves With Electron Beams and Plasmas (World Scientific, 1994); V. K. Tripathi and P. V. Siva Rama Prasad, J. Plasma Phys. 41, 13 (1989); K. Ramachandran and V. K. Tripathi, IEEE Trans. Plasma Sci. 25, 423 (1997)]. In this paper, OTSI is investigated in a magnetized electron-positron-ion plasma. The dispersion relation of the process is established. The pump field threshold, along with the maximum growth rate of the instability is assessed using the Arecibo and HAARP parameters.

  12. Non-thermal enhancement of electron-positron pair creation in burning thermonuclear laboratory plasmas

    Science.gov (United States)

    Hill, E. G.; Rose, S. J.

    2014-12-01

    We estimate the number of electron-positron pairs which will be produced during the burning of a Deuterium-Tritium (DT) plasma in conditions that are anticipated will be achieved at the National Ignition Facility. In particular we consider, for the first time, the effect of including the gamma photons produced in a low probability channel of the DT reaction. It is found that non-thermal effects driven by the fusion products are the dominant method of pair production, and lead to a number density of positrons within the capsule in excess of 3 × 1017 cm-3. The positrons are predominately produced by the Bethe-Heitler process and destroyed by two photon annihilation.

  13. Oscillating two-stream instability in a magnetized electron-positron-ion plasma

    International Nuclear Information System (INIS)

    Oscillating two-stream instability (OTSI) in a magnetized electron-ion plasma has been thoroughly studied, e.g., in ionospheric heating experiments [C. S. Liu and V. K. Tripathi, Interaction of Electromagnetic Waves With Electron Beams and Plasmas (World Scientific, 1994); V. K. Tripathi and P. V. Siva Rama Prasad, J. Plasma Phys. 41, 13 (1989); K. Ramachandran and V. K. Tripathi, IEEE Trans. Plasma Sci. 25, 423 (1997)]. In this paper, OTSI is investigated in a magnetized electron-positron-ion plasma. The dispersion relation of the process is established. The pump field threshold, along with the maximum growth rate of the instability is assessed using the Arecibo and HAARP parameters

  14. Relaxation of a magnetized electron-positron-ion plasma with flows

    International Nuclear Information System (INIS)

    It is shown that possible relaxed magnetic field configurations of a magnetized electron-positron-ion (e-p-i) plasma with flows can be described by a triple curl Beltrami (TCB) equation, which is equivalent to the superposition of three different Beltrami fields. The TCB equation admits three relaxed structures when the linear and nonlinear inertial forces of all three plasma species involved are taken into account. One of the structures represents the system size while the remaining two could be of the order of electron skin depth. -- Highlights: → Relaxed magnetic field configurations satisfy triple curl Beltrami equation. → Relaxed state is characterized by three scale parameters. → Inertial effects play an important role to create Beltrami fields.

  15. Multiplicity distributions in proton-(anti)proton and electron-positron collisions with parton recombination

    CERN Document Server

    Zborovský, I

    2011-01-01

    A new approach to phenomenological description of the charged particle multiplicity distributions in proton-(anti)proton and electron-positron collisions is presented. The observed features of the data are interpreted on the basis of stochastic-physical ideas of multiple production. Besides the processes of parton immigration and absorption, two and three patron incremental and decremental recombinations are considered. The complex behaviour of the multiplicity distributions at different energies is described by four parametric generalized hypergeometric distribution (GHD). Application of the proposed GHD to data measured by the CMS, ALICE, and ATLAS Collaborations suggests that soft multiparton recombination processes can manifest itself significantly in the structure of multiplicity distribution in pp interactions at very high energies.

  16. The Causal approach for the electron-positron scattering in the Generalized Quantum Electrodynamics

    CERN Document Server

    Bufalo, R; Soto, D E

    2014-01-01

    In this paper we study the generalized electrodynamics contribution for the electron-positron scattering process, $e^{-}e^{+}\\rightarrow e^{-}e^{+}$, the Bhabha scattering. Within the framework of the standard model, for energies larger when compared to the electron mass, we calculate the cross section expression for the scattering process. This quantity is usually calculated in the framework of the Maxwell electrodynamics and, by phenomenological reasons, corrected by a cut-off parameter. On the other hand, by considering the generalized electrodynamics instead of Maxwell's, we can show that the effects played by the Podolsky mass is actually a natural cut-off parameter for this scattering process. Furthermore, by means of experimental data of Bhabha scattering we will estimate its lower bound value. Nevertheless, in order to have a mathematically well defined description of our study we shall present our discussion in the framework of the Epstein-Glaser causal theory.

  17. Intellectualised databases of scientific publications abstracts in the field of electron positron annihilation

    International Nuclear Information System (INIS)

    Full text: The report represents a model for application of results, developed in 1978-1999 [1] for creation of innovative Databases (DB) of scientific publications abstracts in the field of electron-positron annihilation (EPA). Electronic DB, provided with intellectualised search and identification technologies of contents of required documents [2]. The practical significance of developing in Uzbekistan the innovative technologies of creating subject and problem oriented information search languages (ISL) applicable to a massive of documents approximately 4-5 thousand units is additionally described in the report. Perspectives of intellectualisation of information technologies in actual directions in science requiring activity are examined: nuclear technologies, nano technologies, Electronic Learning, Computer search systems, computer translation systems, human resources development, innovative economics, etc. [2,3

  18. Semiclassical description of nonlinear electron-positron photoproduction in strong laser fields

    CERN Document Server

    Meuren, Sebastian; Di Piazza, Antonino

    2015-01-01

    The nonlinear Breit-Wheeler process is studied in the presence of strong and short laser pulses. We show that for a relativistically intense plane-wave laser field many aspects of the momentum distribution for the produced electron-positron pair like its extend, region of highest probability and carrier-envelope phase effects can be explained from the classical evolution of the created particles in the background field. To this end we verify that the local constant-crossed field approximation is also appropriate for the calculation of the spectrum if applied on the probability-amplitude level. To compare the exact expressions with the semiclassical approach, we introduce a very fast numerical scheme, which makes it feasible to completely resolve the interference structure of the spectrum over the available multidimensional phase space.

  19. Modulational instability of ion-acoustic wave envelopes in magnetized quantum electron-positron-ion plasmas

    International Nuclear Information System (INIS)

    The amplitude modulation of quantum ion-acoustic waves (QIAWs) along an external magnetic field is studied in a quantum electron-positron-ion (e-p-i) magnetoplasma. Reductive perturbation technique is used to derive the three-dimensional nonlinear Schroedinger equation which governs the slow modulation of QIAW packets. Accounting for the effects of the electron to ion number density ratio (μ), the normalized ion-cyclotron frequency (ωc) as well as the ratio (H) of the 'plasmonic energy density' to the Fermi energy, new regimes for the modulational instability of QIAWs are obtained and analyzed. In contrast to one-dimensional unmagnetized e-p-i plasmas, the instability growth rate is shown to suppress with increasing μ or decreasing the values of H. The predicted results could be important for understanding the salient features of modulated QIAW packets in dense astrophysical plasmas as well as to the next generation intense laser solid density plasma experiments.

  20. Nonlinear interaction of intense electromagnetic waves with a magnetoactive electron-positron-ion plasma

    Energy Technology Data Exchange (ETDEWEB)

    Khorashadizadeh, S. M.; Rastbood, E.; Zeinaddini Meymand, H. [Physics Department, University of Birjand, Birjand (Iran, Islamic Republic of); Niknam, A. R. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of)

    2013-08-15

    The nonlinear coupling between circularly polarized electromagnetic (CPEM) waves and acoustic-like waves in a magnetoactive electron-positron-ion (e-p-i) plasma is studied, taking into account the relativistic motion of electrons and positrons. The possibility of modulational instability and its growth rate as well as the envelope soliton formation and its characteristics in such plasmas are investigated. It is found that the growth rate of modulation instability increases in the case that ω{sub c}/ω<1 (ω{sub c} and ω are the electron gyrofrequency and the CPEM wave frequency, respectively) and decreases in the case that ω{sub c}/ω>1. It is also shown that in a magnetoactive e-p-i plasma, the width of bright soliton increases/decreases in case of (ω{sub c}/ω)<1/(ω{sub c}/ω)>1 by increasing the magnetic field strength.

  1. Oscillating two-stream instability in a magnetized electron-positron-ion plasma

    Energy Technology Data Exchange (ETDEWEB)

    Tinakiche, Nouara [Department of Physics, Faculty of Science, U.M.B.B, Boumerdes 35000 (Algeria); Faculty of Physics, U.S.T.H.B, Algiers 16111 (Algeria); Annou, R. [Faculty of Physics, U.S.T.H.B, Algiers 16111 (Algeria)

    2015-04-15

    Oscillating two-stream instability (OTSI) in a magnetized electron-ion plasma has been thoroughly studied, e.g., in ionospheric heating experiments [C. S. Liu and V. K. Tripathi, Interaction of Electromagnetic Waves With Electron Beams and Plasmas (World Scientific, 1994); V. K. Tripathi and P. V. Siva Rama Prasad, J. Plasma Phys. 41, 13 (1989); K. Ramachandran and V. K. Tripathi, IEEE Trans. Plasma Sci. 25, 423 (1997)]. In this paper, OTSI is investigated in a magnetized electron-positron-ion plasma. The dispersion relation of the process is established. The pump field threshold, along with the maximum growth rate of the instability is assessed using the Arecibo and HAARP parameters.

  2. Cross section for production of low-energy electron-positron pairs by relativistic heavy ions

    Science.gov (United States)

    Eby, P. B.

    1991-01-01

    Starting with the lowest-order unscreened QED matrix element for electron-positron pair production by heavy charged particles, the paper calculates the cross section for this process differential in all independent variables and valid for all pair energies small compared to the incident particle energy. Integration over the possible emission angles of one of the pair members gives an expression that is valid for low-energy pairs that can be compared with previous work based on the Weizsaecker-Williams method. Integration over the possible angles of the other pair member then yields an expression identical to one derived by Racah. The high energy-transfer limit of the expression for the cross section integrated over electron and positron angles is found to be identical to that of Kelner in the unscreened case.

  3. Multibillion-dolalr collider plans unveiled

    CERN Multimedia

    Cartlidge, Edwin

    2007-01-01

    "Particle physicists released an outline design for the proposed International Linear Collider (ILC) at a meeting in Beijing this morning. The design details the components needed to build the 31 km-long facility and comes with and initial estimate of the collider's cost: a cool $6.5bn for the core project. (1 page)

  4. The Next Linear Collider: NLC2001

    Energy Technology Data Exchange (ETDEWEB)

    D. Burke et al.

    2002-01-14

    Recent studies in elementary particle physics have made the need for an e{sup +}e{sup -} linear collider able to reach energies of 500 GeV and above with high luminosity more compelling than ever [1]. Observations and measurements completed in the last five years at the SLC (SLAC), LEP (CERN), and the Tevatron (FNAL) can be explained only by the existence of at least one particle or interaction that has not yet been directly observed in experiment. The Higgs boson of the Standard Model could be that particle. The data point strongly to a mass for the Higgs boson that is just beyond the reach of existing colliders. This brings great urgency and excitement to the potential for discovery at the upgraded Tevatron early in this decade, and almost assures that later experiments at the LHC will find new physics. But the next generation of experiments to be mounted by the world-wide particle physics community must not only find this new physics, they must find out what it is. These experiments must also define the next important threshold in energy. The need is to understand physics at the TeV energy scale as well as the physics at the 100-GeV energy scale is now understood. This will require both the LHC and a companion linear electron-positron collider. A first Zeroth-Order Design Report (ZDR) [2] for a second-generation electron-positron linear collider, the Next Linear Collider (NLC), was published five years ago. The NLC design is based on a high-frequency room-temperature rf accelerator. Its goal is exploration of elementary particle physics at the TeV center-of-mass energy, while learning how to design and build colliders at still higher energies. Many advances in accelerator technologies and improvements in the design of the NLC have been made since 1996. This Report is a brief update of the ZDR.

  5. International linear collider reference design report 2007

    International Nuclear Information System (INIS)

    The International Linear Collider will give physicists a new cosmic doorway to explore energy regimes beyond the reach of today's accelerators. A proposed electron-positron collider, the ILC will complement the Large Hadron Collider, a proton-proton collider at the European Center for Nuclear Research (CERN) in Geneva, Switzerland, together unlocking some of the deepest mysteries in the universe. With LHC discoveries pointing the way, the ILC -- a true precision machine -- will provide the missing pieces of the puzzle. Consisting of two linear accelerators that face each other, the ILC will hurl some 10 billion electrons and their anti-particles, positrons, toward each other at nearly the speed of light. Superconducting accelerator cavities operating at temperatures near absolute zero give the particles more and more energy until they smash in a blazing crossfire at the centre of the machine. Stretching approximately 35 kilometres in length, the beams collide 14,000 times every second at extremely high energies -- 500 billion-electron-volts (GeV). Each spectacular collision creates an array of new particles that could answer some of the most fundamental questions of all time. The current baseline design allows for an upgrade to a 50-kilometre, 1 trillion-electron-volt (TeV) machine during the second stage of the project. This reference design provides the first detailed technical snapshot of the proposed future electron-positron collider, defining in detail the technical parameters and components that make up each section of the 31-kilometer long accelerator. The report will guide the development of the worldwide R and D program, motivate international industrial studies and serve as the basis for the final engineering design needed to make an official project proposal later this decade

  6. International linear collider reference design report

    Energy Technology Data Exchange (ETDEWEB)

    Aarons, G.

    2007-06-22

    The International Linear Collider will give physicists a new cosmic doorway to explore energy regimes beyond the reach of today's accelerators. A proposed electron-positron collider, the ILC will complement the Large Hadron Collider, a proton-proton collider at the European Center for Nuclear Research (CERN) in Geneva, Switzerland, together unlocking some of the deepest mysteries in the universe. With LHC discoveries pointing the way, the ILC -- a true precision machine -- will provide the missing pieces of the puzzle. Consisting of two linear accelerators that face each other, the ILC will hurl some 10 billion electrons and their anti-particles, positrons, toward each other at nearly the speed of light. Superconducting accelerator cavities operating at temperatures near absolute zero give the particles more and more energy until they smash in a blazing crossfire at the centre of the machine. Stretching approximately 35 kilometres in length, the beams collide 14,000 times every second at extremely high energies -- 500 billion-electron-volts (GeV). Each spectacular collision creates an array of new particles that could answer some of the most fundamental questions of all time. The current baseline design allows for an upgrade to a 50-kilometre, 1 trillion-electron-volt (TeV) machine during the second stage of the project. This reference design provides the first detailed technical snapshot of the proposed future electron-positron collider, defining in detail the technical parameters and components that make up each section of the 31-kilometer long accelerator. The report will guide the development of the worldwide R&D program, motivate international industrial studies and serve as the basis for the final engineering design needed to make an official project proposal later this decade.

  7. The Next Linear Collider: NLC2001

    International Nuclear Information System (INIS)

    Recent studies in elementary particle physics have made the need for an e+e- linear collider able to reach energies of 500 GeV and above with high luminosity more compelling than ever [1]. Observations and measurements completed in the last five years at the SLC (SLAC), LEP (CERN), and the Tevatron (FNAL) can be explained only by the existence of at least one particle or interaction that has not yet been directly observed in experiment. The Higgs boson of the Standard Model could be that particle. The data point strongly to a mass for the Higgs boson that is just beyond the reach of existing colliders. This brings great urgency and excitement to the potential for discovery at the upgraded Tevatron early in this decade, and almost assures that later experiments at the LHC will find new physics. But the next generation of experiments to be mounted by the world-wide particle physics community must not only find this new physics, they must find out what it is. These experiments must also define the next important threshold in energy. The need is to understand physics at the TeV energy scale as well as the physics at the 100-GeV energy scale is now understood. This will require both the LHC and a companion linear electron-positron collider. A first Zeroth-Order Design Report (ZDR) [2] for a second-generation electron-positron linear collider, the Next Linear Collider (NLC), was published five years ago. The NLC design is based on a high-frequency room-temperature rf accelerator. Its goal is exploration of elementary particle physics at the TeV center-of-mass energy, while learning how to design and build colliders at still higher energies. Many advances in accelerator technologies and improvements in the design of the NLC have been made since 1996. This Report is a brief update of the ZDR

  8. BEIJING RESTAURANT

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Maxim’s de Paris, Beijing In the late 19th century, Maxim Garcia opened a restaurant, Maxim’s, in Paris. On September 26, 1983, a new Maxim’s de Paris was opened in Beijing, becoming the first Sino-foreign cooperative Western-style restaurant. The interior decorations of Maxim’s de Paris imitate those of Maxim’s in Paris. Entering the restaurant, you will feel you have entered the French royal palace in the 19th century. Maxim’s de Paris Beijing has a dining hall, a coffee house and several bars, being able to accommodate 200 persons for dinner or 300 persons for a cocktail party and buffet. Here, you can enjoy different kinds of delicious food from European countries. Maxim’s cakes are loved by people because of their unique taste and style. At present, the restaurant is promoting a type of sugarless cake for those who dislike or cannot eat sugar. For more than 20 years, Maxim’s de Paris Beijing has consistently provided top-notch service and food. Welcome to Maxim’s de Paris Beijing to enjoy your life! Address: No.2 Chongwenmen Xidajie, Beijing Tel: 86-10-6512-1992

  9. Creation of electron-positron pairs at excited Landau levels by neutrino in a strong magnetic field

    CERN Document Server

    Kuznetsov, A V; Savin, V N

    2014-01-01

    The process of neutrino production of electron positron pairs in a magnetic field of arbitrary strength, where electrons and positrons can be created in the states corresponding to excited Landau levels, is analysed. The mean value of the neutrino energy loss due to the process $\

  10. The Higgs Physics Program at the International Linear Collider

    CERN Document Server

    Strube, Jan

    2015-01-01

    The International Linear Collider (ILC) is a proposed electron -- positron collider with a collision energy of $\\sqrt{s}$ = 500 GeV in the baseline configuration. The ILC physics program takes full advantage of the fact that the machine can be operated at arbitrary energy from the maximum down to the peak of the ZH production cross section near $\\sqrt{s}$ = 250 GeV or below. It will advance our understanding of nature through precision measurements of Standard Model parameters, detailed study of the Higgs sector, and a comprehensive search for new phenomena that extends beyond the purely kinematic reach. This note gives an overview of the ILC Higgs program.

  11. The standard model Higgs search at the large hadron collider

    Indian Academy of Sciences (India)

    Satyaki Bhattacharya; on behalf of the CMS and the ATLAS Collaborations

    2007-11-01

    The experiments at the large hadron collider (LHC) will probe for Higgs boson in the mass range between the lower bound on the Higgs mass set by the experiments at the large electron positron collider (LEP) and the unitarity bound (∼ 1 TeV). Strategies are being developed to look for signatures of Higgs boson and measure its properties. In this paper results from full detector simulation-based studies on Higgs discovery from both ATLAS and CMS experiments at the LHC will be presented. Results of simulation studies on Higgs coupling measurement at LHC will be discussed.

  12. Remembering Beijing

    Institute of Scientific and Technical Information of China (English)

    Ian Corbett

    2012-01-01

    Every General Assembly is remembered for something - in the past few years, Sydney for starting the International Year of Astronomy, Prague for Pluto, and Rio de Janeiro for the Strategic Plan. 1 thought that Beijing would be remembered for restructuring the Divisions and for the impressive progress we have made in implementing the Strategic Plan. But I was wrong! Above all, Beijing will be remembered for the unobtrusive but impeccable organization, the overwhelming generosity of our hosts, the smiling teams of volunteers, and the impressive CNCC.

  13. Beijing Time

    OpenAIRE

    Dutton, Michael; Lo, Hsiu-ju Stacy; Wu, Dong Dong

    2010-01-01

    “Where is the market?” inquires the tourist one dark, chilly morning. “Follow the ghosts,” responds the taxi driver, indicating a shadowy parade of overloaded tricycles. “It’s not called the ghost market for nothing!” And indeed, Beijing is nothing if not haunted. Among the soaring skyscrapers, choking exhaust fumes, nonstop traffic jams, and towering monuments, one discovers old Beijing—newly styled, perhaps, but no less present and powerful than in its ancient incarnation. Beijing Time cond...

  14. Parametric decays in relativistic magnetized electron-positron plasmas with relativistic temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Rodrigo A.; Munoz, Victor [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Asenjo, Felipe A. [Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States); Alejandro Valdivia, J. [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y la Nanotecnologia, CEDENNA, Santiago (Chile)

    2012-08-15

    The nonlinear evolution of a circularly polarized electromagnetic wave in an electron-positron plasma propagating along a constant background magnetic field is considered, by studying its parametric decays. Relativistic effects, of the particle motion in the wave field and of the plasma temperature, are included to obtain the dispersion relation of the decays. The exact dispersion relation of the pump wave has been previously calculated within the context of a relativistic fluid theory and presents two branches: an electromagnetic and an Alfven one. We investigate the parametric decays for the pump wave in these two branches, including the anomalous dispersion zone of the Alfven branch where the group velocity is negative. We solve the nonlinear dispersion relation for different pump wave amplitudes and plasma temperatures, finding various resonant and nonresonant wave couplings. We are able to identify these couplings and study their behavior as we modify the plasma parameters. Some of these couplings are suppressed for larger amplitudes or temperatures. We also find two kinds of modulational instabilities, one involving two sideband daughter waves and another involving a forward-propagating electroacoustic mode and a sideband daughter wave.

  15. Propagation of ultra-intense electromagnetic waves through electron-positron-ion plasma

    Science.gov (United States)

    Rozina, Ch.; Tsintsadze, N. L.; Jamil, M.

    2016-07-01

    A kinetic approach is used to study the propagation of ultrarelativistic (amplitude) electromagnetic waves through electron-positron-ion plasma. For our purposes, we formulate a new plasma particle distribution function in the presence of ultrarelativistically intense circularly polarized electromagnetic (EM) waves. An effective dispersion relation of constant amplitude ultrarelativistic EM wave is derived, skin depth is calculated in particular, frequency regimes and has shown numerically that the penetration depth increases with the amplitude of ultra-intense electromagnetic waves, λ s k ˜ a /1 2 , i.e., plasma will be heated more in the region of skin depth. Next, we have found that the nonlinear interaction of ultrarelativistically intense EM waves of time and space varying amplitude leads to construct kinetic nonlinear Schrödinger equation (KNSE), containing both local and non-local nonlinear terms, where nonlocal nonlinear term appears due to density perturbations of plasma species. Taking the effects of the latter into consideration, nonlinear Landau damping is discussed for KNSE, damping rate is computed, and numerically ultrarelativistic EM waves are shown to decay exponentially. The present results should be helpful to understand the specific properties of the ultrarelativistic EM waves in astrophysical plasmas, e.g., pulsars, black holes, and neutron stars.

  16. Oblique propagation of ion-acoustic solitary waves in a magnetized electron-positron-ion plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ferdousi, M.; Sultana, S.; Mamun, A. A. [Department of Physics, Jahangirnagar University, Savar, Dhaka-1342 (Bangladesh)

    2015-03-15

    The properties of obliquely propagating ion-acoustic solitary waves in the presence of ambient magnetic field have been investigated theoretically in an electron-positron-ion nonthermal plasma. The plasma nonthermality is introduced via the q-nonextensive distribution of electrons and positrons. The Korteweg-de Vries (K-dV) and modified K-dV (mK-dV) equations are derived by adopting reductive perturbation method. The solution of K-dV and modified K-dV equation, which describes the solitary wave characteristics in the long wavelength limit, is obtained by steady state approach. It is seen that the electron and positron nonextensivity and external magnetic field (obliqueness) have significant effects on the characteristics of solitary waves. A critical value of nonextensivity is found for which solitary structures transit from positive to negative potential. The findings of this investigation may be used in understanding the wave propagation in laboratory and space plasmas where static external magnetic field is present.

  17. The terminal bulk Lorentz factor of relativistic electron-positron jet

    CERN Document Server

    Renaud, N

    1997-01-01

    We present numerical simulation of bulk Lorentz factor of relativistic electron positron jet driven by Compton rocket effect from accretion disk radiation. The plasma is assumed to have a power-law energy distribution and is continuously reheated to compensate for radiation losses. We include Klein-Nishina (hereafter KN) corrections, and study the role of energy upper cut-off, spectral index, and source compactness. We determine terminal bulk Lorentz factor in the case of supermassive black holes relevant to AGN and stellar black holes relevant to galactic microquasars. In the latter case, effects of KN corrections are more important and induce terminal bulk Lorentz factor smaller than in the former case. The result can explain the low bulk Lorentz factors for galactic sources (GRS1915+105, GROJ1655-40) compared to extragalactic ones. We also take into account the influence of the size of the accretion disk; if the external radius is small enough, the bulk Lorentz factor can be as high as 60, which is compara...

  18. The terminal bulk Lorentz factor of relativistic electron-positron jets

    CERN Document Server

    Renaud, N

    1998-01-01

    We present numerical simulation of bulk Lorentz factor of relativistic electron-positron jet driven by Compton rocket effect from accretion disc radiation. The plasma is assumed to have a power-law distribution $n_{e}(\\gamma) \\propto \\gamma^{-s}$ whith $1 < \\gamma< \\gamma_{max}$ and is continuously reheated to compensate for radiation losses. We include full Klein-Nishina (hereafter KN) cross section, and study the role of energy upper cut-off $\\gamma_{max}$, spectral index $s$, and source compactness. We determine terminal bulk Lorentz factor in the case of supermassive black holes relevant to AGN and stellar black holes relevant to galactic microquasars. In the latter case, Klein-Nishina cross section effect are more important, and induce terminal bulk Lorentz factor smaller than in the former case. Our result are in good agreement with bulk Lorentz factors observed in galactic sources (GRS1915+105, GROJ1655-40) and extragalactic ones. Differences in scattered radiation and acceleration mechanism effi...

  19. Nonlinear Landau damping and modulation of electrostatic waves in a nonextensive electron-positron pair plasma

    CERN Document Server

    Chatterjee, D

    2015-01-01

    The nonlinear theory of amplitude modulation of electrostatic wave envelopes in a collisionless electron-positron (EP) pair plasma is studied by using a set of Vlasov-Poisson equations in the context of Tsallis' $q$-nonextensive statistics. In particular, the previous linear theory of Langmuir oscillations in EP plasmas [Phys. Rev. E {\\bf87}, 053112 (2013)] is rectified and modified. Applying the multiple scale technique (MST), it is shown that the evolution of electrostatic wave envelopes is governed by a nonlinear Schr{\\"o}dinger (NLS) equation with a nonlocal nonlinear term $\\propto {\\cal{P}}\\int|\\phi(\\xi',\\tau)|^2d\\xi'\\phi/(\\xi-\\xi') $ [where ${\\cal P}$ denotes the Cauchy principal value, $\\phi$ is the small-amplitude electrostatic (complex) potential, and $\\xi$ and $\\tau$ are the stretched coordinates in MST] which appears due to the wave-particle resonance. It is found that a subregion $1/3

  20. Semiclassical picture for electron-positron photoproduction in strong laser fields

    Science.gov (United States)

    Meuren, Sebastian; Keitel, Christoph H.; Di Piazza, Antonino

    2016-04-01

    The nonlinear Breit-Wheeler process is studied in the presence of strong and short laser pulses. We show that for a relativistically intense plane-wave laser field many features of the momentum distribution of the produced electron-positron pair like its extension, region of highest probability and carrier-envelope phase effects can be explained from the classical evolution of the created particles in the background field. To this end an intuitive semiclassical picture based on the local constant-crossed field approximation applied on the probability-amplitude level is established and compared with the standard approach used in QED-PIC codes. The main difference is the substructure of the spectrum, which results from interference effects between macroscopically separated formation regions. In order to compare the predictions of the semiclassical approach with exact calculations, a very fast numerical scheme is introduced. It renders the calculation of the fully differential spectrum on a grid which resolves all interference fringes feasible. Finally, the difference between classical and quantum absorption of laser four-momentum in the process is pointed out and the dominance of the former is proven. As a self-consistent treatment of the quantum absorption is not feasible within existing QED-PIC approaches, our results provide reliable error estimates relevant for regimes where the laser depletion due to a developing QED cascade becomes significant.

  1. Overview of laser-driven generation of electron-positron beams

    Science.gov (United States)

    Sarri, G.; Dieckmann, M. E.; Kourakis, I.; di Piazza, A.; Reville, B.; Keitel, C. H.; Zepf, M.

    2015-08-01

    Electron-positron (e-p) plasmas are widely thought to be emitted, in the form of ultra-relativistic winds or collimated jets, by some of the most energetic or powerful objects in the Universe, such as black-holes, pulsars, and quasars. These phenomena represent an unmatched astrophysical laboratory to test physics at its limit and, given their immense distance from Earth (some even farther than several billion light years), they also provide a unique window on the very early stages of our Universe. However, due to such gigantic distances, their properties are only inferred from the indirect interpretation of their radiative signatures and from matching numerical models: their generation mechanism and dynamics still pose complicated enigmas to the scientific community. Small-scale reproductions in the laboratory would represent a fundamental step towards a deeper understanding of this exotic state of matter. Here we present recent experimental results concerning the laser-driven production of ultra-relativistic e-p beams. In particular, we focus on the possibility of generating beams that present charge neutrality and that allow for collective effects in their dynamics, necessary ingredients for the testing pair-plasma physics in the laboratory. A brief discussion of the analytical and numerical modelling of the dynamics of these plasmas is also presented in order to provide a summary of the novel plasma physics that can be accessed with these objects. Finally, general considerations on the scalability of laboratory plasmas up to astrophysical scenarios are given.

  2. c-Axis projected electron-positron momentum density in YBa2Cu3O7

    International Nuclear Information System (INIS)

    The authors present the theoretical c-axis projected electron-positron momentum density N2γ(Px,py) in YBa2Cu3O7 based on the local density approximation (LDA) framework along various lines in momentum space. The calculations use the Korringa-Kohn-Rostoker (KKR) band structure formalism. The anisotropic distribution defined by taking cuts through the calculated spectra along different lines in the (px,py) plane possesses complex structures which arise from both Fermi surface effects and the anisotropy of the smoothly varying underlying background from filled bands; the maximum size of the anisotropy is about 10% of N2γ(0,0). The theoretically predicted N2γ(px,y) distribution is compared with the measured 2D-ACAR spectrum. The considerations suggest that in interpreting the 2D-ACAR data on YBa2Cu3O7 in terms of a band theory LDA picture, a substantial, largely isotropic, background should be subtracted from both the 2D-ACAR's and the associated LCW-folded spectra

  3. Nonlinear Landau damping and modulation of electrostatic waves in a nonextensive electron-positron-pair plasma

    Science.gov (United States)

    Chatterjee, Debjani; Misra, A. P.

    2015-12-01

    The nonlinear theory of amplitude modulation of electrostatic wave envelopes in a collisionless electron-positron (EP) pair plasma is studied by using a set of Vlasov-Poisson equations in the context of Tsallis' q -nonextensive statistics. In particular, the previous linear theory of Langmuir oscillations in EP plasmas [Saberian and Esfandyari-Kalejahi, Phys. Rev. E 87, 053112 (2013), 10.1103/PhysRevE.87.053112] is rectified and modified. Applying the multiple scale technique (MST), it is shown that the evolution of electrostatic wave envelopes is governed by a nonlinear Schrödinger (NLS) equation with a nonlocal nonlinear term ∝P ∫|ϕ (ξ',τ ) |2d ξ'ϕ /(ξ -ξ') [where P denotes the Cauchy principal value, ϕ is the small-amplitude electrostatic (complex) potential, and ξ and τ are the stretched coordinates in MST], which appears due to the wave-particle resonance. It is found that a subregion 1 /3 modulational instability of wave envelopes, as well as on the solitary wave solution of the NLS equation. It is found that the modulated wave packet is always unstable (nonlinear Landau damping) due to the nonlocal nonlinearity in the NLS equation. Furthermore, the effect of the nonlinear Landau damping is to slow down the amplitude of the wave envelope, and the corresponding decay rate can be faster the larger is the number of superthermal particles in pair plasmas.

  4. Hadron production in electron-positron annihilation computed from the gauge-gravity correspondence

    International Nuclear Information System (INIS)

    We provide a nonperturbative expression for the hadron production in electron-positron annihilation at zero temperature in a strongly coupled, large-Nc SU(Nc) field theory with Nfc quark flavors. The resulting expressions are valid to leading order in the electromagnetic coupling constant but nonperturbatively in the SU(Nc) interactions and the mass of the quark. We obtain this quantity by computing the imaginary part of the hadronic vacuum polarization function Πq using holographic techniques, providing an alternative to the known method that uses the spectrum of infinitely stable mesons determined by the normalizable modes of the appropriated fields in the bulk. Our result exhibits a structure of poles localized at specific real values of q2, which coincide with the ones found using the normalizable modes, and extends it offering the unique analytic continuation of this distribution to a function defined for values of q2 over the complex plane. This analytic continuation permits to include a finite decay width for the mesons. By comparison with experimental data we find qualitatively good agreement on the shape of the first pole, when using the ρ meson parameters and choosing a proper normalization factor. We then estimate the contribution to the anomalous magnetic moment of the muon finding an agreement within 25%, for this choice of parameters.

  5. Collider physics

    International Nuclear Information System (INIS)

    Generally, all experiments with particle physics using energetic beams is collider physics. Today technically collider is taken to mean a particle accelerator in which two beams travelling in opposite directions collide. Many important discoveries in the last 25 years are from collider physics

  6. Continua Beijing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    From January 1 to March 30, 2008,Continua Beijing will host a solo exhibition of Italian contem- porary art master Michelangelo Pistoletto for the first time. Born in 1933,Michelangelo Pistoletto hehl his first solo exhi- hition in Dulin,Italy,and created a series of artworks named after painted objects.These artworks

  7. BEIJING BOUND

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Capital to one fifth of mankind and the fastest developing nation in history, Beijing is attracting a growing number of foreign residents drawn by interest and opportunity.The city is in thrall to incredibly rapid development that is altering its appearance and character.So what can the new arrivals expect?

  8. Boycott Beijing?

    Science.gov (United States)

    Goldstein, Evan R.

    2008-01-01

    In the wake of China's harsh suppression of antigovernment protests in Tibet--among other human-rights abuses throughout its territory--world leaders have faced mounting pressure to boycott the opening ceremonies of the approaching Olympic Games in Beijing. The boycott has also become a hot topic on the presidential-campaign trail. John McCain and…

  9. Effect of positron wave function on positron annihilation rates and electron-positron momentum densities in solids

    Energy Technology Data Exchange (ETDEWEB)

    Rubaszek, A. [Polska Akademia Nauk, Wroclaw (Poland). Inst. Niskich Temperatur i Badan Strukturalnych; Szotek, Z.; Temmerman, W.M. [Daresbury Lab. (United Kingdom)

    2001-07-01

    To interpret positron annihilation data in solids in terms of the electron momentum density and electron charge distribution, both the electron-positron interaction and positron wave function have to be considered explicitly. In the present work we discuss the effect of the shape of the positron wave function on the calculated positron annihilation rates in a variety of solids, for different types of electrons (core, s, p, d, f). We show that the form of the positron distribution in the Wigner-Seitz cell has a crucial effect on the resulting core electron contribution to the positron annihilation characteristics. The same is observed for the localised d and f electrons in transition metals Finally we study the influence of the positron wave function on the electron-positron momentum density in elemental Si. (orig.)

  10. Interference Effects in Electron-Positron Pair Creation by the Interaction of a Bichromatic Laser Field and a Nucleus

    Energy Technology Data Exchange (ETDEWEB)

    Augustin, Sven; Mueller, Carsten [Heinrich-Heine Universitaet, Duesseldorf (Germany)

    2013-07-01

    We investigate quantum interferences in electron-positron pair creation in the collision of a relativistic nuclear beam and an intense laser pulse. In particular, we consider a laser field consisting of two modes with commensurate frequencies. In this situation, quantum path interference may arise which can lead to an increase or a decrease of the total pair production rate. The interference is also visible in angular differential rates which are discussed both in the nuclear rest frame and the laboratory frame.

  11. On the reliability of various enhancement theories for a description of electron-positron densities in metals

    Energy Technology Data Exchange (ETDEWEB)

    Sormann, H. [Technische Univ., Graz (Austria). Inst. fuer Theoretische Physik; Kontrym-Sznajd, G. [Polska Akademia Nauk, Wroclaw (Poland). Inst. Niskich Temperatur i Badan Strukturalnych; West, R.N. [Texas Univ., Arlington, TX (United States). Dept. of Physics

    2001-07-01

    Four theoretical approaches to calculate momentum densities of electron-positron annihilation pairs (MDAP) in crystalline solids are confronted with 3D densities reconstructed from two-dimensional angular correlation (2D-ACAR) data for copper, chromium, and yttrium. It is shown that the Bloch-modified ladder theory, in contrast to other approaches, is able to describe - at least qualitatively - the MDAP profiles for all metals investigated. (orig.)

  12. Jet production in the CoLoRFulNNLO method: event shapes in electron-positron collisions

    CERN Document Server

    Del Duca, Vittorio; Kardos, Adam; Somogyi, Gábor; Szőr, Zoltán; Trócsányi, Zoltán; Tulipánt, Zoltán

    2016-01-01

    We present the CoLoRFulNNLO method to compute higher order radiative corrections to jet cross sections in perturbative QCD. We apply our method to the computation of event shape observables in electron-positron collisions at NNLO accuracy and validate our code by comparing our predictions to previous results in the literature. We also calculate for the first time jet cone energy fraction at NNLO.

  13. Effect of q-nonextensive parameter and saturation time on electron density steepening in electron-positron-ion plasmas

    International Nuclear Information System (INIS)

    The effect of q-nonextensive parameter and saturation time on the electron density steepening in electron-positron-ion plasmas is studied by particle in cell method. Phase space diagrams show that the size of the holes, and consequently, the number of trapped particles strongly depends on the q-parameter and saturation time. Furthermore, the mechanism of the instability and exchange of energy between electron-positron and electric field is explained by the profiles of the energy density. Moreover, it is found that the q-parameter, saturation time, and electron and positron velocities affect the nonlinear evolution of the electron density which leads to the steepening of its structure. The q-nonextensive parameter or degree of nonextensivity is the relation between temperature gradient and potential energy of the system. Therefore, the deviation of q-parameter from unity indicates the degree of inhomogeneity of temperature or deviation from equilibrium. Finally, using the kinetic theory, a generalized q-dispersion relation is presented for electron-positron-ion plasma systems. It is found that the simulation results in the linear regime are in good agreement with the growth rate results obtained by the kinetic theory

  14. Dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Asit, E-mail: asit-saha123@rediffmail.com, E-mail: prasantachatterjee1@rediffmail.com [Department of Mathematics, Sikkim Manipal Institute of Technology, Majitar, Rangpo, East-Sikkim 737136 (India); Department of Mathematics, Siksha Bhavana, Visva Bharati University, Santiniketan-731235 (India); Pal, Nikhil; Chatterjee, Prasanta, E-mail: asit-saha123@rediffmail.com, E-mail: prasantachatterjee1@rediffmail.com [Department of Mathematics, Siksha Bhavana, Visva Bharati University, Santiniketan-731235 (India)

    2014-10-15

    The dynamic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas with superthermal electrons and positrons has been investigated in the framework of perturbed and non-perturbed Kadomtsev-Petviashili (KP) equations. Applying the reductive perturbation technique, we have derived the KP equation in electron-positron-ion magnetoplasma with kappa distributed electrons and positrons. Bifurcations of ion acoustic traveling waves of the KP equation are presented. Using the bifurcation theory of planar dynamical systems, the existence of the solitary wave solutions and the periodic traveling wave solutions has been established. Two exact solutions of these waves have been derived depending on the system parameters. Then, using the Hirota's direct method, we have obtained two-soliton and three-soliton solutions of the KP equation. The effect of the spectral index κ on propagations of the two-soliton and the three-soliton has been shown. Considering an external periodic perturbation, we have presented the quasi periodic behavior of ion acoustic waves in electron-positron-ion magnetoplasmas.

  15. Highlights from CERN: The CLIC Project for a Future e$^{+}$e$^{−}$ Linear Collider

    CERN Document Server

    Tecker, Frank

    2007-01-01

    A high luminosity ( 10$^{34}$-10$^{35}$ cm$^{2}$/s) linear electron-positron Collider (CLIC) with a nominal centre-of-mass energy of 3 TeV is under study in the framework of an international collaboration of laboratories and institutes, with the aim to provide the HEP community with a new facility for the post LHC era. After a brief introduction of the physics motivation, the CLIC scheme to extend Linear Colliders into the Multi-TeV colliding beam energy range will be described. In the following, the main challenges and the very promising achievements already obtained will be presented.

  16. The Detector and Interaction Region for a Photon Collider at TESLA

    CERN Document Server

    Rosca, A

    2004-01-01

    TESLA is designed as an electron-positron linear collider (LC) based on super-conducting technology. A second interaction region is forseen to be incorporated in the design allowing its possible operation as a photon collider. In this paper I describe the basic design of the $\\gamma \\gamma$ interaction region taking into account the beam-beam and laser related issuses and review some aspects of other accelerator components such as the feedback system and the beam dump which are critical to the operation of TESLA as a photon collider.

  17. Insight into the electron-positron correlations in metals through the looking glass

    Science.gov (United States)

    Rubaszek, Anna

    2016-05-01

    A semi-empirical analysis of the positron annihilation experimental spectra indicates for a strong sensitivity of the two-particle electron-positron (e-p) enhancement factor to the l=s, p, d, f character of the initial electronic state [1,2]. The essential discrepancy between the models consists in the dependence of the relevant correlation functions on the energy of the annihilating electron. The present contribution contains a theoretical study of the e-p enhancement factors for s, p, d and f states as a function of the electron energy. The slope of the resulting characteristics is directly related to the degree of localisation of the s, p, d and f electrons in the electron density of states. This effect occurs especially for d electrons in transition metals, in favour to the approach of Ref. [1]. The energy dependence of the two-particle correlation functions is also a source of controversy between various theoretical approaches. The energy dependent enhancement factors describe properly the positron interaction with delocalised s and p electrons, but this approach overestimates the high momentum components of the e-p momentum densities, dominated by the localised d and f states. On the contrary, the calculations that employ the energy averaged enhancement factors match better with experiment for localised d and f electrons, but they hardly reproduce experimental spectra for nearly-free electron populations. An attempt to visit two sides of the looking glass is made in the theory of the present work. The model combines the properties of both approaches. The resulting e-p momentum densities and enhancement factors are in good agreement with the experimental data for simple, noble and transition metals, both in the low and high momentum region.

  18. Nonlinear Landau damping and modulation of electrostatic waves in a nonextensive electron-positron-pair plasma

    Science.gov (United States)

    Chatterjee, Debjani; Misra, A. P.

    2015-12-01

    The nonlinear theory of amplitude modulation of electrostatic wave envelopes in a collisionless electron-positron (EP) pair plasma is studied by using a set of Vlasov-Poisson equations in the context of Tsallis' q -nonextensive statistics. In particular, the previous linear theory of Langmuir oscillations in EP plasmas [Saberian and Esfandyari-Kalejahi, Phys. Rev. E 87, 053112 (2013), 10.1103/PhysRevE.87.053112] is rectified and modified. Applying the multiple scale technique (MST), it is shown that the evolution of electrostatic wave envelopes is governed by a nonlinear Schrödinger (NLS) equation with a nonlocal nonlinear term ∝P ∫|ϕ (ξ',τ ) |2d ξ'ϕ /(ξ -ξ') [where P denotes the Cauchy principal value, ϕ is the small-amplitude electrostatic (complex) potential, and ξ and τ are the stretched coordinates in MST], which appears due to the wave-particle resonance. It is found that a subregion 1 /3

  19. The extent of non-thermal particle acceleration in relativistic, electron-positron reconnection

    Energy Technology Data Exchange (ETDEWEB)

    Werner, Greg [University of Colorado; Guo, Fan [Los Alamos National Laboratory

    2015-07-21

    Reconnection is studied as an explanation for high-energy flares from the Crab Nebula. The production of synchrotron emission >100 MeV challenges classical models of acceleration. 3D simulation shows that reconnection, converting magnetic energy to kinetic energy, can accelerate beyond γrad. The power-law index and high-energy cutoff are important for understanding the radiation spectrum dN/dγ = f(γ) ∝ γ. α and cutoff were measured vs. L and σ, where L is system (simulation) size and σ is upstream magnetization (σ = B2/4πnmc2). α can affect the high-energy cutoff. In conclusion, for collisionless relativistic reconnection in electron-positron plasma, without guide field, nb/nd=0.1: (1) relativistic magnetic reconnection yields power-law particle spectra, (2) the power law index decreases as σ increases, approaching ≈1.2. (3) the power law is cut off at an energy related to acceleration within a single current layer, which is proportional to the current layer length (for small systems, that length is the system length, yielding γc2 ≈ 0.1 L/ρ0; for large systems, the layer length is limited by secondary tearing instability, yielding γc1 ≈ 4σ; the transition from small to large is around L/ρ0 = 40σ.). (4) although the large-system energy cutoff is proportional to the average energy per particle, it is significantly higher than the average energy per particle.

  20. Higgs Measurement at e+e- Circular Colliders

    CERN Document Server

    Ruan, M

    2014-01-01

    Now that the mass of the Higgs boson is known, circular electron positron colliders, able to measure the properties of these particles with high accuracy, are receiving considerable attention. Design studies have been launched (i) at CERN with the Future Circular Colliders (FCC), of which an e+e- collider is a potential first step (FCC-ee, formerly caller TLEP) and (ii) in China with the Circular Electron Positron Collider (CEPC). Hosted in a tunnel of at least 50 km (CEPC) or 80-100 km (FCC), both projects can deliver very high luminosity from the Z peak to HZ threshold (CEPC) and even to the top pair threshold and above (FCC-ee). At the ZH production optimum, around 240 GeV, the FCC-ee (CEPC) will be able to deliver 10 (5) ab-1 integrated luminosity in 5 (10) years with 4 (2) interaction points: hence to produce millions of Higgs bosons through the Higgsstrahlung process and vector boson fusion processes. This sample opens the possibility of subper-cent precision absolute measurements of the Higgs boson cou...

  1. BEIJING RESTAURANTS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Mare in Beijing Mare draws its name from the Latin for "ocean," representing both the Southern European and Mediterranean influences on the cuisine of the restaurant as well as the beautiful and peaceful ambience the restaurant affords. Mare offers high-quality, specialized Spanish cuisine, served with care by the Spanish chef. "Tapas are particular dishes of Spain, and Mare promotes 30 kinds of tapas for customers to appreci-

  2. UNJAMMING BEIJING

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Building a livable city may start with the development of a comfortable and efficient public transport system Commuters on Beijing’s city rail transport system received a gift from the Beijing Municipal Government on October 7,the last day of the seven-day National Day holiday. From the first working day on October 8,the price of a single unlimited length journey dropped from five yuan to two.The drop

  3. Monte Carlo event generation of photon-photon collisions at colliders

    CERN Document Server

    Helenius, Ilkka

    2015-01-01

    In addition to being interesting in itself, the photon-photon interactions will be an inevitable background for the future electron-positron colliders. Thus to be able to quantify the potential of future electron-positron colliders it is important to have an accurate description of these collisions. Here we present our ongoing work to implement the photon-photon collisions in the Pythia 8 event generator. First we introduce photon PDFs in general and then discuss in more detail one particular set we have used in our studies. Then we will discuss how the parton-shower algorithm in Pythia 8 is modified in case of photon beams and how the beam remnants are constructed. Finally a brief outlook on future developments is given.

  4. FCC Based Lepton-Hadron and Photon-Hadron Colliders: Luminosity and Physics

    CERN Document Server

    Acar, Y C; Beser, S; Karadeniz, H; Kaya, U; Oner, B B; Sultansoy, S

    2016-01-01

    Construction of future electron-positron colliders (or dedicated electron linac) and muon colliders (or dedicated muon ring) tangential to Future Circular Collider (FCC) will give opportunity to utilize highest energy proton and nucleus beams for lepton-hadron and photon-hadron collisions. Luminosity values of FCC based ep, \\mup, eA, \\muA, \\gammap and \\gammaA colliders are estimated. Multi-TeV center of mass energy ep colliders based on the FCC and linear colliders (LC) are considered in detail. Parameters of upgraded versions of the FCC proton beam are determined to optimize luminosity of electron-proton collisions keeping beam-beam effects in mind. Numerical calculations are performed using a currently being developed collision point simulator. It is shown that L_{ep}\\sim10^{32}\\,cm^{-2}s^{-1} can be achieved with LHeC-like upgrade of the FCC parameters.

  5. Composite Higgs: searches for new physics at future $e^+e^-$ colliders

    CERN Document Server

    Barducci, Daniele; Moretti, Stefano; Pruna, Giovanni Marco

    2013-01-01

    In this proceeding, we extend a previous analysis concerning the prospects of a future electron-positron collider in testing the 4-Dimensional Composite Higgs Model. In particular, we introduce two motivated benchmarks and study them in Higgs-Strahlung, for three possible energy stages and different luminosity options of such a machine and confront our results to the expected experimental accuracies in the various accessible Higgs decay channels.

  6. CP violation in electron-positron and proton-antiproton collisions

    International Nuclear Information System (INIS)

    In this thesis possible CP tests in e-+e-- and panti p collisions were presented and analyzed. In chapter 3 3-jet exclusive and 2-jet inclusive reactions of the electron-positron scattering were considered. It is shown that one is here sensitive to possible CP violation in the anti qqZG vertex with the dimensionless coupling constants hqA,V for the vector and the axial-vector contribution. By means of Monte Carlo calculations it can be shown that couplings hqA,V of 0.3 at a c. m. energy of 200 GeV respectively 0.06 at a c. m. energy of 500 GeV can still be detected. In chapter 4 the density matrix of the Z boson was analyzed, which is produced in the reaction anti p+p→Z+jet+X. Also in this experiment it is possible to test CP violation in the effective vertex anti qqZG. The density matrix of the Z boson was decomposed into cartesic tensors and the coefficients of this decomposition plotted in dependence of the pseudorapidity (2 values) and the transverse momentum of the Z boson in diagrams. If in the framework of the measurement accuracy CP violation is present the dimensionless vector and axial-vector coupling constants for the CP violating four-vertex anti qqZG must be smaller than O(10-1) at 105 produced Z bosons and a c. m. energy of 630 GeV. In this reaction also a possibility resulted to determine by measurement of the tensor polarization of the Z boson the gluon distribution function. In chapter 5 briefly a CP test was discussed, which is sensitive to possible CP violation in the 3-gluon vertex in the reaction anti p+p→3jets+X. For 106 possible events (for a c. m. energy of 630 GeV) for the coupling constant as bound 0.32x10-3 GeV-2 can be given. (orig./HSI)

  7. The Contribution of Millisecond Pulsars to the Local Electron / Positron Spectrum

    Science.gov (United States)

    Venter, Christo; Buesching, Ingo; Harding, Alice; Kopp, Andreas; Gonthier, Peter

    The high energies of gamma-ray photons (as well as the presence of lower-energy photons) coupled with the intense magnetic fields characterizing younger pulsars enable formation of electron-positron pair cascades which fills the pulsar magnetosphere with plasma and also feeds an outflowing particle wind that may create a surrounding pulsar wind nebula (PWN). Although this scenario was originally thought to be unique to the younger pulsar population, Fermi LAT demonstrated that the light curves of millisecond pulsars (MSPs) are generally very similar to those of younger pulsars, requiring copious pair production even for this older class with much lower surface magnetic fields and spin-down power. These pair cascades may thus be a primary source of Galactic electrons and positrons, and may present an astrophysical explanation for the observed enhancement in positron flux in the high-energy band. We investigate Galactic MSPs contribution to the flux of local cosmic-ray electrons and positrons. We use a population synthesis code to predict the source properties (number, position, and power) of the present-day Galactic MSPs, taking into account the latest Fermi observations to calibrate the model output. Next, we simulate pair cascade spectra from these MSPs using a model that invokes an offset-dipole magnetic field, as this increases the pair production rate relative to a standard dipole field geometry. The model source pair spectra may extend to several TeV, depending on pulsar properties, neutron star equation of state, and magnetic polar cap offset. Since MSPs are not surrounded by PWNe or supernova shells, we can assume that the pairs escape from the pulsar environment without energy loss and undergo losses only in the intergalactic medium. We lastly compute the spectrum of the transported electrons and positrons at Earth, following their diffusion and energy loss through the Galaxy. We will compare our results with the observed local interstellar spectrum and

  8. Hydrodynamic and kinetic models for spin-1/2 electron-positron quantum plasmas: Annihilation interaction, helicity conservation, and wave dispersion in magnetized plasmas

    International Nuclear Information System (INIS)

    We discuss the complete theory of spin-1/2 electron-positron quantum plasmas, when electrons and positrons move with velocities mach smaller than the speed of light. We derive a set of two fluid quantum hydrodynamic equations consisting of the continuity, Euler, spin (magnetic moment) evolution equations for each species. We explicitly include the Coulomb, spin-spin, Darwin and annihilation interactions. The annihilation interaction is the main topic of the paper. We consider the contribution of the annihilation interaction in the quantum hydrodynamic equations and in the spectrum of waves in magnetized electron-positron plasmas. We consider the propagation of waves parallel and perpendicular to an external magnetic field. We also consider the oblique propagation of longitudinal waves. We derive the set of quantum kinetic equations for electron-positron plasmas with the Darwin and annihilation interactions. We apply the kinetic theory to the linear wave behavior in absence of external fields. We calculate the contribution of the Darwin and annihilation interactions in the Landau damping of the Langmuir waves. We should mention that the annihilation interaction does not change number of particles in the system. It does not related to annihilation itself, but it exists as a result of interaction of an electron-positron pair via conversion of the pair into virtual photon. A pair of the non-linear Schrodinger equations for the electron-positron plasmas including the Darwin and annihilation interactions is derived. Existence of the conserving helicity in electron-positron quantum plasmas of spinning particles with the Darwin and annihilation interactions is demonstrated. We show that the annihilation interaction plays an important role in the quantum electron-positron plasmas giving the contribution of the same magnitude as the spin-spin interaction

  9. Hydrodynamic and kinetic models for spin-1/2 electron-positron quantum plasmas: Annihilation interaction, helicity conservation, and wave dispersion in magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, Pavel A., E-mail: andreevpa@physics.msu.ru [Faculty of Physics, Lomonosov Moscow State University, Moscow (Russian Federation)

    2015-06-15

    We discuss the complete theory of spin-1/2 electron-positron quantum plasmas, when electrons and positrons move with velocities mach smaller than the speed of light. We derive a set of two fluid quantum hydrodynamic equations consisting of the continuity, Euler, spin (magnetic moment) evolution equations for each species. We explicitly include the Coulomb, spin-spin, Darwin and annihilation interactions. The annihilation interaction is the main topic of the paper. We consider the contribution of the annihilation interaction in the quantum hydrodynamic equations and in the spectrum of waves in magnetized electron-positron plasmas. We consider the propagation of waves parallel and perpendicular to an external magnetic field. We also consider the oblique propagation of longitudinal waves. We derive the set of quantum kinetic equations for electron-positron plasmas with the Darwin and annihilation interactions. We apply the kinetic theory to the linear wave behavior in absence of external fields. We calculate the contribution of the Darwin and annihilation interactions in the Landau damping of the Langmuir waves. We should mention that the annihilation interaction does not change number of particles in the system. It does not related to annihilation itself, but it exists as a result of interaction of an electron-positron pair via conversion of the pair into virtual photon. A pair of the non-linear Schrodinger equations for the electron-positron plasmas including the Darwin and annihilation interactions is derived. Existence of the conserving helicity in electron-positron quantum plasmas of spinning particles with the Darwin and annihilation interactions is demonstrated. We show that the annihilation interaction plays an important role in the quantum electron-positron plasmas giving the contribution of the same magnitude as the spin-spin interaction.

  10. Observation of antideuteron production in electron-positron annihilation at 10 GeV center of mass energy

    International Nuclear Information System (INIS)

    The production of antideuterons has been observed in electron-positron annihilations at center-of-mass energies around 10 GeV. Antideuterons have been identified unambiguously by their energy loss in the drift chamber, their time-of-flight and the pattern of their energy deposition in the shower counters of the ARGUS detector. The production rate in the momentum range (0.6-1.8)GeV/c is (1.6sub(-0.7)sup(+1.0))) X 10-5 per hadronic event. (orig.)

  11. Dust charge fluctuation effects on dust ion-acoustic waves in dusty electron-positron-ion plasmas

    International Nuclear Information System (INIS)

    In this paper, using the kinetic theory the longitudinal dielectric permittivity in a plasma consisting of electrons, positrons, ions and negatively charged dust grains is obtained, taking into account dust charge fluctuations. It is shown that the dust charge fluctuations can lead to either the damping or growing of dust ion-acoustic waves. We find a critical wave number above which these waves grow. Also, we numerically investigate the critical wave number and the growth rate of these waves for different plasma parameters. (paper)

  12. Positron 2D-ACAR experiments and electron-positron momentum density in YBa2Cu3OP7-x

    International Nuclear Information System (INIS)

    This paper discusses positron annihilation (2D-ACAR) measurements in the c-projection on an untwinned metallic single crystal of YBa2Cu3O7-x as a function of temperature, for five temperatures ranging from 30K to 300K. The measured 2D-ACAR intensities are interpreted in terms of the electron-positron momentum density obtained within the KKR-band theory framework. The temperature dependence of the 2D-ACAR spectra is used to extract a background corrected experimental spectrum which is in remarkable accord with the corresponding band theory predictions, and displays in particular clear signatures of the electron ridge Fermi surface

  13. Electron-positron momentum density distribution of Gd from 2D ACAR data via maximum entropy and Cormack's methods

    International Nuclear Information System (INIS)

    A successful application of the maximum entropy method (MEM) to the reconstruction of electron-positron momentum density distribution in gadolinium out of the experimental of 2D ACAR data is presented. Formally, the algorithm used was prepared for two-dimensional reconstructions from line integrals. For the first time the results of MEM, applied to such data, are compared in detail with the ones obtained by means of Cormack's method. It is also shown how the experimental uncertainties may influence the results of the latter analysis. Preliminary calculations, using WIEN2k code, of band structure and Fermi surface have been done as well. (orig.)

  14. Electron-positron momentum density distribution of Gd from 2D ACAR data via Maximum Entropy and Cormack's methods

    Science.gov (United States)

    Pylak, M.; Kontrym-Sznajd, G.; Dobrzyński, L.

    2011-08-01

    A successful application of the Maximum Entropy Method (MEM) to the reconstruction of electron-positron momentum density distribution in gadolinium out of the experimental of 2D ACAR data is presented. Formally, the algorithm used was prepared for two-dimensional reconstructions from line integrals. For the first time the results of MEM, applied to such data, are compared in detail with the ones obtained by means of Cormack's method. It is also shown how the experimental uncertainties may influence the results of the latter analysis. Preliminary calculations, using WIEN2k code, of band structure and Fermi surface have been done as well.

  15. Annihilation of the electron-positron pairs in the positronium ion Ps$^-$ and bi-positronium Ps$_2$

    OpenAIRE

    Frolov, Alexei M.

    2009-01-01

    Rates of the two-, three-, four- and five-photon annihilations of the electron-positron pairs are determined numerically for the three-body positronium ion Ps$^-$ ($e^- e^+ e^-$) and four-body bi-positronium `molecule' Ps$_2$ ($e^- e^+ e^- e^+$). The values obtained in our computations are $\\Gamma_{2 \\gamma}($Ps$^-) \\approx$ 2.08048530525$\\cdot 10^{9}$ $sec^{-1}$, $\\Gamma_{3 \\gamma}($Ps$^-) \\approx$ 5.6364151550$\\cdot 10^{6}$ $sec^{-1}$, $\\Gamma_{4 \\gamma}($Ps$^-) \\approx$ 3.075$\\cdot 10^{3}$...

  16. The Large Hadron Collider in the LEP tunnel

    International Nuclear Information System (INIS)

    The status of the studies for the CERN Large Hadron Collider (LHC) is described. This collider will provide proton-proton collisions with 16 TeV centre-of-mass energy and a luminosity exceeding 1033 cm-2 s-1 per interaction point. It can be installed in the tunnel of the Large Electron-Positron Storage Ring (LEP) above the LEP elements. It will use superconducting magnets of a novel, compact design, having two horizontally separated channels for the two counter-rotating bunched proton beams, which can collide in a maximum of seven interaction points. Collisions between protons of the LHC and electrons of LEP are also possible with a centre-of-mass energy of up to 1.8 TeV and a luminosity of up to 2 x 1032 cm-2 s-1. (orig.)

  17. Physics Opportunities at a Photon-Photon Collider

    OpenAIRE

    Brodsky, Stanley J.

    2002-01-01

    The advent of back-scattered laser beams for electron-positron colliders will allow detailed studies of a large array of high energy photon-photon and photon-electron collision processes with polarized beams. These include tests of electroweak theory in photon-photon annihilation such as $\\gamma \\gamma \\to W^+ W^-$, $\\gamma \\gamma \\to $ Higgs bosons, and higher-order loop processes, such as $\\gamma \\gamma \\to \\gamma \\gamma, Z \\gamma, H^0 Z^0$ and $Z Z.$ Methods for measuring the anomalous mag...

  18. On the rich eight branch spectrum of the oblique propagating longitudinal waves in partially spin polarized electron-positron-ion plasmas

    CERN Document Server

    Andreev, Pavel A

    2016-01-01

    We consider the separate spin evolution of electrons and positrons in electron-positron and electron-positron-ion plasmas. We consider oblique propagating longitudinal waves in this systems. We report presence of the spin-electron acoustic waves and their dispersion dependencies. In electron-positron plasmas, similarly to the electron-ion plasmas, we find one spin-electron acoustic wave (SEAW) at propagation parallel or perpendicular to the external field and two spin-electron acoustic waves at the oblique propagation. At the parallel or perpendicular propagation of the longitudinal waves in electron-positron-ion plasmas we find four branches: the Langmuir wave, the positron-acoustic wave and pair of waves having spin nature, they are the SEAW and, as we called it, spin-electron-positron acoustic wave (SEPAW). At the oblique propagation we find eight longitudinal waves: the Langmuir wave, Trivelpiece-Gould wave, pair of positron-acoustic waves, pair of SEAWs, and pair of SEPAWs. Thus, for the first time, we r...

  19. Rich eight-branch spectrum of the oblique propagating longitudinal waves in partially spin-polarized electron-positron-ion plasmas

    Science.gov (United States)

    Andreev, Pavel A.; Iqbal, Z.

    2016-03-01

    We consider the separate spin evolution of electrons and positrons in electron-positron and electron-positron-ion plasmas. We consider the oblique propagating longitudinal waves in these systems. Working in a regime of high-density n0˜1027cm-3 and high-magnetic-field B0=1010 G, we report the presence of the spin-electron acoustic waves and their dispersion dependencies. In electron-positron plasmas, similarly to the electron-ion plasmas, we find one spin-electron acoustic wave (SEAW) at the propagation parallel or perpendicular to the external field and two spin-electron acoustic waves at the oblique propagation. At the parallel or perpendicular propagation of the longitudinal waves in electron-positron-ion plasmas, we find four branches: the Langmuir wave, the positron-acoustic wave, and a pair of waves having spin nature, they are the SEAW and the wave discovered in this paper, called the spin-electron-positron acoustic wave (SEPAW). At the oblique propagation we find eight longitudinal waves: the Langmuir wave, the Trivelpiece--Gould wave, a pair of positron-acoustic waves, a pair of SEAWs, and a pair of SEPAWs. Thus, for the first time, we report the existence of the second positron-acoustic wave existing at the oblique propagation and the existence of SEPAWs.

  20. Muon colliders

    International Nuclear Information System (INIS)

    Muon Colliders have unique technical and physics advantages and disadvantages when compared with both hadron and electron machines. They should thus be regarded as complementary. Parameters are given of 4 TeV and 0.5 TeV high luminosity micro+micro-colliders, and of a 0.5 TeV lower luminosity demonstration machine. We discuss the various systems in such muon colliders, starting from the proton accelerator needed to generate the muons and proceeding through muon cooling, acceleration and storage in a collider ring. Problems of detector background are also discussed

  1. Study of four-lepton final states in electron-positron interactions at 29 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Petradza, A.

    1989-08-01

    This thesis presents a study of electron-positron scattering to four light leptons. The motivations behind it are twofold. Firstly, the study is a test of the theory of electron-positron interactions to 4th order in the fine structure constant {alpha}. A deviation from the theory could indicate the existence of a heavy new particle. Secondly, a measurement of these processes may prove useful in the understanding of other QED-type reactions. The method for simulating the four-lepton processes by the Monte Carlo event generator of Berends, Daverveldt and Kleiss is described. Theoretical predictions are compared to data from the Mark II and HRS experiments at the PEP storage ring. The observed events consist of four leptons at large angles. Data for all three e{sup +}e{sup -}e{sup +}e{sup -}, e{sup +}e{sup -}{mu}{sup +}{mu}{sup -} and {mu}{sup +}{mu}{sup -}{mu}{sup +}{mu}{sup -} processes are well described by the QED Monte Carlo calculation. The various kinematical distributions are in good agreement with QED to order {alpha}{sup 4}. 18 refs., 64 figs., 19 tabs.

  2. Modified Zakharov-Kuznetsov equation for a non-uniform electron-positron-ion magnetoplasma with kappa-distributed electrons

    Science.gov (United States)

    Ahmad, Ali; Masood, W.

    2015-10-01

    > We investigate the low-frequency (by comparison with the ion Larmor frequency) electrostatic solitary structures in a spatially non-uniform electron-positron-ion (e-p-i) magnetoplasma with non-Maxwellian electrons. A linear dispersion relation for the obliquely propagating ion acoustic drift wave is derived and it is shown that the non-Maxwellian electron population modifies the dispersion characteristics of the wave under consideration. We also carry out a nonlinear analysis and derive the modified Zakharov-Kuznetsov (MZK) equation for the coupled drift acoustic wave in a non-uniform magnetized plasma. We highlight the differences between the MZK equation and its homogeneous counterpart. We also find the solution of the MZK equation using the tangent hyperbolic method. It is observed that the electron spectral index , positron concentration, and propagation angle alter the structure of the ion acoustic drift solitary waves. The results obtained in this paper may be beneficial to understanding the propagation characteristics of electrostatic drift solitary structures in the interstellar medium and in laboratory experiments where electron-positron plasmas have recently been created by impinging ultra-intense laser pulses on a solid density target at the Lawrence Livermore National Laboratory (LLNL).

  3. Study of four-lepton final states in electron-positron interactions at 29 GeV

    International Nuclear Information System (INIS)

    This thesis presents a study of electron-positron scattering to four light leptons. The motivations behind it are twofold. Firstly, the study is a test of the theory of electron-positron interactions to 4th order in the fine structure constant α. A deviation from the theory could indicate the existence of a heavy new particle. Secondly, a measurement of these processes may prove useful in the understanding of other QED-type reactions. The method for simulating the four-lepton processes by the Monte Carlo event generator of Berends, Daverveldt and Kleiss is described. Theoretical predictions are compared to data from the Mark II and HRS experiments at the PEP storage ring. The observed events consist of four leptons at large angles. Data for all three e+e-e+e-, e+e-μ+μ- and μ+μ-μ+μ- processes are well described by the QED Monte Carlo calculation. The various kinematical distributions are in good agreement with QED to order α4. 18 refs., 64 figs., 19 tabs

  4. Modulational instability and envelope excitation of ion-acoustic waves in quantum electron-positron-ion plasmas

    International Nuclear Information System (INIS)

    The theoretical study of modulational instability (MI) and localized envelope excitations of finite amplitude ion-acoustic waves (IAWs) is revisited in an unmagnetized quantum electron-positron-ion plasma. For this purpose, a one-dimensional nonlinear Schroedinger equation, which governs the slow modulation of IAW packets, is derived by using the standard reductive perturbations technique. Two parameters, defining the ratio of the electron to ion number density (μ) and the quantum coupling parameter (H) describing the ratio of the 'plasmonic energy density' to the Fermi energy density, are shown to play crucial roles in determining the modulational stability/MI domains, as well as for the existence of both bright and dark envelope solitons. It is found that the stability region increases (decreases) with increasing μ(H), whereas the MI region for the IAW mode shifts to larger (smaller) wave number k as the value of μ(H) increases. Moreover, the parameter H is shown to suppress the MI growth rate of the IAWs. The present results may be relevant to dense astrophysical plasmas (e.g., white dwarfs, where the electron-positron annihilation can be important, and where the particle density is of the order of 1034-1035 m-3) as well as to the next generation intense laser solid density plasma experiments.

  5. Imprints of Electron-positron Winds on the Multi-wavelength Afterglows of Gamma-ray Bursts

    CERN Document Server

    Geng, J J; Huang, Y F; Li, L; Dai, Z G

    2016-01-01

    Optical re-brightenings in the afterglows of some gamma-ray bursts (GRBs) are unexpected within the framework of the simple external shock model. While it has been suggested that the central engines of some GRBs are newly born magnetars, we aim to relate the behaviors of magnetars to the optical re-brightenings. A newly born magnetar will lose its rotational energy in the form of Poynting-flux, which may be converted into a wind of electron-positron pairs through some magnetic dissipation processes. As proposed by Dai (2004), this wind will catch up with the GRB outflow and a long-lasting reverse shock would form. By applying this scenario to GRB afterglows, we find that the reverse shock propagating back into the electron-positron wind can lead to an observable optical re-brightening and a simultaneous X-ray plateau (or X-ray shallow decay). In our study, we select four GRBs, i.e., GRB 080413B, GRB 090426, GRB 091029, and GRB 100814A, of which the optical afterglows are well observed and show clear re-bright...

  6. Meson spectroscopy viewed from J//PSI/ decay: Gluonic states at BEPC

    Energy Technology Data Exchange (ETDEWEB)

    Chanowitz, M.S.

    1987-07-01

    The theoretical and experimental status of the search for gluonic states is reviewed. Progress clearly requires much higher statistics studies of J//psi/ decay, as will be possible at the Beijing Electron Positron Collider. 83 refs.

  7. Meson spectroscopy viewed from J//PSI/ decay: Gluonic states at BEPC

    International Nuclear Information System (INIS)

    The theoretical and experimental status of the search for gluonic states is reviewed. Progress clearly requires much higher statistics studies of J//psi/ decay, as will be possible at the Beijing Electron Positron Collider. 83 refs

  8. Hydrodynamic and kinetic models for spin-1/2 electron-positron quantum plasmas: Annihilation interaction, helicity conservation, and wave dispersion in magnetized plasmas

    CERN Document Server

    Andreev, Pavel A

    2014-01-01

    We discuss complete theory of spin-1/2 electron-positron quantum plasmas, when electrons and positrons move with velocities mach smaller than the speed of light. We derive a set of two fluid quantum hydrodynamic equations consisting of the continuity, Euler, spin (magnetic moment) evolution equations for each species. We explicitly include the Coulomb, spin-spin, Darwin and annihilation interactions. The annihilation interaction is the main topic of the paper. We consider contribution of the annihilation interaction in the quantum hydrodynamic equations and in spectrum of waves in magnetized electron-positron plasmas. We consider propagation of waves parallel and perpendicular to an external magnetic field. We also consider oblique propagation of longitudinal waves. We derive set of quantum kinetic equations for electron-positron plasmas with the Darwin and annihilation interactions. We apply the kinetic theory for the linear wave behavior in absence of external fields. We calculate contribution of the Darwin...

  9. The Detector and Interaction Region for a Photon Collider at TESLA

    OpenAIRE

    Rosca, Aura

    2003-01-01

    TESLA is designed as an electron-positron linear collider (LC) based on super-conducting technology. A second interaction region is forseen to be incorporated in the design allowing its possible operation as a photon collider. In this paper I describe the basic design of the $\\gamma \\gamma$ interaction region taking into account the beam-beam and laser related issuses and review some aspects of other accelerator components such as the feedback system and the beam dump which are critical to th...

  10. Interaction Region for a 100 TeV Proton-Proton Collider

    CERN Document Server

    Martin, R; Dalena, B

    2015-01-01

    As part of its post-LHC high energy physics program, CERN is conducting a study for a new proton-proton collider, FCC-hh, running at center-of-mass energies of up to 100 TeV, pushing the energy frontier of fundamental physics to a new limit. At a circumference of 80-100 km, this machine is planned to use the same tunnel as FCC-ee, a proposed 90-350 GeV high luminosity electron-positron collider. This paper presents the design progress and technical challenges for the interaction region of FCC-hh.

  11. Probing light-quark Yukawa couplings via hadronic event shapes at lepton colliders

    CERN Document Server

    Gao, Jun

    2016-01-01

    We propose a novel idea for probing the Higgs boson couplings through the measurement of hadronic event shape distributions in the decay of the Higgs boson at lepton colliders. The method provides a unique test of the Higgs boson couplings and of QCD effects in the decay of the Higgs boson. It can be used to directly probe the Yukawa couplings of the light quarks and to further test the mechanism of electroweak symmetry breaking. From a case study for the proposed Circular Electron-Positron Collider, light-quark couplings with a strength greater than 8% of the bottom-quark Yukawa coupling in the standard model can be excluded.

  12. Unique radiation problems associated with the SLAC Linear Collider

    International Nuclear Information System (INIS)

    The SLAC Linear Collider (SLC) is a variation of a new class of linear colliders whereby two linear accelerators are aimed at each other to collide intense bunches of electrons and positrons together. Conventional storage rings are becoming ever more costly as the energy of the stored beams increases such that the cost of two linear colliders per GeV is less than that of electron-positron storage rings at cm energies above about 100 GeV. The SLC being built at SLAC is designed to achieve a center-of-mass energy of 100 GeV by accelerating intense bunches of particles, both electrons and positrons, in the SLAC linac and transporting them along two different arcs to a point where they are focused to a small radius and made to collide head on. The SLC has two main goals. The first is to develop the physics and technology of linear colliders. The other is to achieve center-of-mass energies above 90 GeV in order to investigate the unification of the weak and electromagnetic interactions in the energy range above 90 GeV; (i.e., Z0, etc.). This note discusses a few of the special problems that were encountered by the Radiation Physics group at SLAC during the design and construction of the SLAC Linear Collider. The nature of these problems is discussed along with the methods employed to solve them

  13. Recent results in electron-positron and lepton-hadron interactions

    International Nuclear Information System (INIS)

    These lectures will start with a few remarks on detectors and beams used to study e+e- annihilation and deep inelastic lepton-nucleon interactions. The main part of the lectures will discuss recent results obtained from a study of these processes including a discussion on the result of recent particle searches. The picture which emerges from these data is consistant with what has become known as the standard model. However, it is important to bear in mind that the experiments so far have only investigated masses which are small compared to 100 GeV/c2, the characteristic mass of the weak interaction. The new generation of e+e- and ep collider will allow us to extend these measurements into a mass range above 100 GeV/c2, and thus provide answers to many of the questions confronting the standard model. (orig./HSI)

  14. Muon Colliders

    OpenAIRE

    Palmer, R. B.; Sessler, A.; Skrinsky, A.; Tollestrup, A.

    1996-01-01

    Muon Colliders have unique technical and physics advantages and disadvantages when compared with both hadron and electron machines. They should thus be regarded as complementary. Parameters are given of 4 TeV and 0.5 TeV high luminosity \\mumu colliders, and of a 0.5 TeV lower luminosity demonstration machine. We discuss the various systems in such muon colliders, starting from the proton accelerator needed to generate the muons and proceeding through muon cooling, acceleration and storage in ...

  15. Elliptically polarized electromagnetic waves in a magnetized quantum electron-positron plasma with effects of exchange-correlation

    CERN Document Server

    Shahmansouri, M

    2016-01-01

    The dispersion properties of elliptically polarized electromagnetic (EM) waves in a magnetized electron-positron-pair (EP-pair) plasma are studied with the effects of particle dispersion associated with the Bohm potential, the Fermi degenerate pressure, and the exchange-correlation force. Two possible modes of the extraordinary or X wave, modified by these quantum effects, are identified and their propagation characteristics are investigated numerically. It is shown that the upper-hybrid frequency, and the cutoff and resonance frequencies are no longer constants but are dispersive due to these quantum effects. It is found that the particle dispersion and the exchange-correlation force can have different dominating roles on each other depending on whether the X waves are of short or long wavelengths (in comparison with the Fermi Debye length). The present investigation should be useful for understanding the collective behaviors of EP plasma oscillations and the propagation of extraordinary waves in magnetized ...

  16. Electronic factors for K-shell-electron conversion probability and electron-positron pair formation probability in electric monopole transitions

    International Nuclear Information System (INIS)

    This paper presents, in tabular form, the electronic factors ΩK,π(Z,k) of the electric monopole transition probability associated with the internal conversion of an electron from the atomic K shell (IC;K) and with the internal pair formation(IPF;π). The Ωπ values are calculated by taking the nuclear Coulomb effects into account. The corrections to ΩK due to finite nuclear size and bound-state atomic screening are not included in the present calculations. The calculated ratio of the K-shell-electron conversion probability to the electron-positron pair formation probability is found to be in good agreement with the available experimental data for Z-<40

  17. The interaction of two nonplanar solitary waves in electron-positron-ion plasmas: An application in active galactic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    EL-Labany, S. K.; Khedr, D. M. [Department of Physics, Faculty of Science, Damietta University, Damietta El-Gedida 34517 (Egypt); El-Shamy, E. F. [Department of Physics, Faculty of Science, Damietta University, Damietta El-Gedida 34517 (Egypt); Department of Physics, College of Science, King Khalid University, P.O. 9004, Abha (Saudi Arabia); Sabry, R. [Department of Physics, Faculty of Science, Damietta University, Damietta El-Gedida 34517 (Egypt); Department of Physics, College of Science and Humanitarian Studies, Salman bin Abdulaziz University, Alkharj (Saudi Arabia)

    2013-01-15

    In the present research paper, the effect of bounded nonplanar (cylindrical and spherical) geometry on the interaction between two nonplanar electrostatic solitary waves (NESWs) in electron-positron-ion plasmas has been studied. The extended Poincare-Lighthill-Kuo method is used to obtain nonplanar phase shifts after the interaction of the two NESWs. This study is a first attempt to investigate nonplanar phase shifts and trajectories for NESWs in a two-fluid plasma (a pair-plasma) consisting of electrons and positrons, as well as immobile background positive ions in nonplanar geometry. The change of phase shifts and trajectories for NESWs due to the effect of cylindrical geometry, spherical geometry, the physical processes (either isothermal or adiabatic), and the positions of two NESWs are discussed. The present investigation may be beneficial to understand the interaction between two NESWs that may occur in active galactic nuclei.

  18. Time-dependent PIC - Monte Carlo modeling of electron-positron cascade in the polar cap of pulsar

    International Nuclear Information System (INIS)

    Many previously proposed models for polar cap cascades (and almost all quantitative models) assumed stationary particle outflow. Predictions of such models disagree with both observational data (e.g. the number of electron-positron pairs in the Crab nebula is ∼ 100 higher than predicted) and results of numerical models of force-free pulsar magnetosphere (the current density required to support force-free magnetosphere differs substantially from what stationary model for PC cascade predicts). On the other hand, the stability of stationary models has not been quantitatively studied. We decided to study the problem from the first principles, namely to model the accelerating electric field, particle acceleration and pair production simultaneously. We developed a hybrid Particle-In-Cell-Monte Carlo code for direct self-consistent time-dependent modeling of polar cap cascades. Here we report the first results of cascade modeling using the current 1D version of the code. (author)

  19. Multi-dimensional instability of obliquely propagating ion acoustic solitary waves in electron-positron-ion superthermal magnetoplasmas

    Energy Technology Data Exchange (ETDEWEB)

    EL-Shamy, E. F., E-mail: emadel-shamy@hotmail.com [Department of Physics, Faculty of Science, Damietta University, New Damietta 34517, Egypt and Department of Physics, College of Science, King Khalid University, Abha P.O. 9004 (Saudi Arabia)

    2014-08-15

    The solitary structures of multi–dimensional ion-acoustic solitary waves (IASWs) have been considered in magnetoplasmas consisting of electron-positron-ion with high-energy (superthermal) electrons and positrons are investigated. Using a reductive perturbation method, a nonlinear Zakharov-Kuznetsov equation is derived. The multi-dimensional instability of obliquely propagating (with respect to the external magnetic field) IASWs has been studied by the small-k (long wavelength plane wave) expansion perturbation method. The instability condition and the growth rate of the instability have been derived. It is shown that the instability criterion and their growth rate depend on the parameter measuring the superthermality, the ion gyrofrequency, the unperturbed positrons-to-ions density ratio, the direction cosine, and the ion-to-electron temperature ratio. Clearly, the study of our model under consideration is helpful for explaining the propagation and the instability of IASWs in space observations of magnetoplasmas with superthermal electrons and positrons.

  20. Positron-acoustic shock waves associated with cold viscous positron fluid in superthermal electron-positron-ion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, M. J., E-mail: josim.phys2007@gmail.com; Alam, M. S.; Mamun, A. A. [Department of Physics, Jahangirnagar University, Savar, Dhaka 1342 (Bangladesh)

    2015-06-15

    A theoretical investigation is made on the positron-acoustic (PA) shock waves (SHWs) in an unmagnetized electron-positron-ion plasma containing immobile positive ions, cold mobile positrons, and hot positrons and electrons following the kappa (κ) distribution. The cold positron kinematic viscosity is taken into account, and the reductive perturbation method is used to derive the Burgers equation. It is found that the viscous force acting on cold mobile positron fluid is a source of dissipation and is responsible for the formation of the PA SHWs. It is also observed that the fundamental properties of the PA SHWs are significantly modified by the effects of different parameters associated with superthermal (κ distributed) hot positrons and electrons.

  1. Self-modulation of nonlinear waves in a weakly magnetized relativistic electron-positron plasma with temperature.

    Science.gov (United States)

    Asenjo, Felipe A; Borotto, Felix A; Chian, Abraham C-L; Muñoz, Víctor; Valdivia, J Alejandro; Rempel, Erico L

    2012-04-01

    We develop a nonlinear theory for self-modulation of a circularly polarized electromagnetic wave in a relativistic hot weakly magnetized electron-positron plasma. The case of parallel propagation along an ambient magnetic field is considered. A nonlinear Schrödinger equation is derived for the complex wave amplitude of a self-modulated wave packet. We show that the maximum growth rate of the modulational instability decreases as the temperature of the pair plasma increases. Depending on the initial conditions, the unstable wave envelope can evolve nonlinearly to either periodic wave trains or solitary waves. This theory has application to high-energy astrophysics and high-power laser physics. PMID:22680585

  2. Self-modulation of nonlinear Alfvén waves in a strongly magnetized relativistic electron-positron plasma.

    Science.gov (United States)

    López, Rodrigo A; Asenjo, Felipe A; Muñoz, Víctor; Chian, Abraham C-L; Valdivia, J A

    2013-08-01

    We study the self-modulation of a circularly polarized Alfvén wave in a strongly magnetized relativistic electron-positron plasma with finite temperature. This nonlinear wave corresponds to an exact solution of the equations, with a dispersion relation that has two branches. For a large magnetic field, the Alfvén branch has two different zones, which we call the normal dispersion zone (where dω/dk>0) and the anomalous dispersion zone (where dω/dkmodulational instability decreases as the temperature is increased. We also study the Alfvén wave propagation in the anomalous dispersion zone, where a nonlinear wave equation is obtained. However, in this zone the wave envelope can evolve only as a periodic wave train. PMID:24032950

  3. Heating and Non-thermal Particle Acceleration in Relativistic, Transverse Magnetosonic Shock Waves in Proton-Electron-Positron Plasmas

    CERN Document Server

    Amato, E; Amato, Elena; Arons, Jonathan

    2006-01-01

    We report the results of 1D particle-in-cell simulations of ultrarelativistic shock waves in proton-electron-positron plasmas. We consider magnetized shock waves, in which the upstream medium carries a large scale magnetic field, directed transverse to the flow. Relativistic cyclotron instability of each species as the incoming particles encounter the increasing magnetic field within the shock front provides the basic plasma heating mechanism. The most significant new results come from simulations with mass ratio $m_p/m_\\pm = 100$. We show that if the protons provide a sufficiently large fraction of the upstream flow energy density (including particle kinetic energy and Poynting flux), a substantial fraction of the shock heating goes into the formation of suprathermal power-law spectra of pairs. Cyclotron absorption by the pairs of the high harmonic ion cyclotron waves, emitted by the protons, provides the non-thermal acceleration mechanism. As the proton fraction increases, the non-thermal efficiency increas...

  4. Neutrino and Electron-positron Pair Emission from Phase-induced Collapse of Neutron Stars to Quark Stars

    CERN Document Server

    Cheng, K S

    2010-01-01

    We study the energy released from phase-transition induced collapse of neutron stars, which results in large amplitude stellar oscillations. To model this process we use a Newtonian hydrodynamic code, with a high resolution shock-capturing scheme. The physical process considered is a sudden phase transition from normal nuclear matter to a mixed phase of quark and nuclear matter. We show that both the temperature and the density at the neutrinosphere oscillate with time. However, they are nearly 180 degree out of phase. Consequently, extremely intense, pulsating neutrino/antineutrino and leptonic pair fluxes will be emitted. During this stage several mass ejecta can be ejected from the stellar surface by the neutrinos and antineutrinos. These ejecta can be further accelerated to relativistic speeds by the electron/positron pairs, created by the neutrino and antineutrino annihilation outside the stellar surface. We suggest that this process may be a possible mechanism for short Gamma-Ray Bursts.

  5. Ion Colliders

    CERN Document Server

    Fischer, W

    2014-01-01

    High-energy ion colliders are large research tools in nuclear physics to study the Quark-Gluon-Plasma (QGP). The range of collision energy and high luminosity are important design and operational considerations. The experiments also expect flexibility with frequent changes in the collision energy, detector fields, and ion species. Ion species range from protons, including polarized protons in RHIC, to heavy nuclei like gold, lead and uranium. Asymmetric collision combinations (e.g. protons against heavy ions) are also essential. For the creation, acceleration, and storage of bright intense ion beams, limits are set by space charge, charge change, and intrabeam scattering effects, as well as beam losses due to a variety of other phenomena. Currently, there are two operating ion colliders, the Relativistic Heavy Ion Collider (RHIC) at BNL, and the Large Hadron Collider (LHC) at CERN.

  6. Beyond the Large Hadron Collider: a first look at cryogenics for CERN future circular colliders

    CERN Document Server

    Lebrun, Ph

    2015-01-01

    Following the first experimental discoveries at the Large Hadron Collider (LHC) and the recent update of the European strategy in particle physics, CERN has undertaken an international study of possible future circular colliders beyond the LHC. The study, conducted with the collaborative participation of interested institutes world-wide, considers several options for very high energy hadron-hadron, electron-positron and hadron-electron colliders to be installed in a quasi-circular underground tunnel in the Geneva basin, with a circumference of 80 km to 100 km. All these machines would make intensive use of advanced superconducting devices, i.e. high-field bending and focusing magnets and/or accelerating RF cavities, thus requiring large helium cryogenic systems operating at 4.5 K or below. Based on preliminary sets of parameters and layouts for the particle colliders under study, we discuss the main challenges of their cryogenic systems and present first estimates of the cryogenic refrigeration capacities req...

  7. Neutrino Factory and Muon Collider Fellow

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, Gail G. [Univ. of California, Riverside, CA (United States); Snopak, Pavel [Univ. of California, Riverside, CA (United States); Bao, Yu [Univ. of California, Riverside, CA (United States)

    2015-03-20

    Muons are fundamental particles like electrons but much more massive. Muon accelerators can provide physics opportunities similar to those of electron accelerators, but because of the larger mass muons lose less energy to radiation, allowing more compact facilities with lower operating costs. The way muon beams are produced makes them too large to fit into the vacuum chamber of a cost-effective accelerator, and the short muon lifetime means that the beams must be reduced in size rather quickly, without losing too many of the muons. This reduction in size is called "cooling." Ionization cooling is a new technique that can accomplish such cooling. Intense muon beams can then be accelerated and injected into a storage ring, where they can be used to produce neutrino beams through their decays or collided with muons of the opposite charge to produce a muon collider, similar to an electron-positron collider. We report on the research carried out at the University of California, Riverside, towards producing such muon accelerators, as part of the Muon Accelerator Program based at Fermilab. Since this research was carried out in a university environment, we were able to involve both undergraduate and graduate students.

  8. 2001 Report on the Next Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    Gronnberg, J; Breidenbach; Burke, D; Corlett, J; Dombeck, T; Markiewicz, T

    2001-08-28

    Recent studies in elementary particle physics have made the need for an e{sup +}e{sup -} linear collider able to reach energies of 500 GeV and above with high luminosity more compelling than ever [1]. Observations and measurements completed in the last five years at the SLC (SLAC), LEP (CERN), and the Tevatron (FNAL) can be explained only by the existence of at least one particle or interaction that has not yet been directly observed in experiment. The Higgs boson of the Standard Model could be that particle. The data point strongly to a mass for the Higgs boson that is just beyond the reach of existing colliders. This brings great urgency and excitement to the potential for discovery at the upgraded Tevatron early in this decade, and almost assures that later experiments at the LHC will find new physics. But the next generation of experiments to be mounted by the world-wide particle physics community must not only find this new physics, they must find out what it is. These experiments must also define the next important threshold in energy. The need is to understand physics at the TeV energy scale as well as the physics at the 100-GeV energy scale is now understood. This will require both the LHC and a companion linear electron-positron collider.

  9. The International Linear Collider - Physics and Perspectives

    CERN Document Server

    ,

    2016-01-01

    With the discovery of a Higgs boson at LHC, all particles of the Standard Model seem to have been observed experimentally, yet many questions are left unanswered. The discovery has intensified the planning for future high-energy colliders, which aim to probe the Standard Model and the mechanism of electroweak symmetry breaking with higher precision and to extend and complement the search for new particles currently under way at the LHC. The most mature option for such a future facility is the International Linear Collider ILC, an electron-positron collider with a centre-of-mass energy of 500 GeV, and the potential for upgrades into the TeV region. The ILC will fully explore the Higgs sector, including model-independent coupling and width measurements, direct measurements of the coupling to the top quark and the Higgs self-coupling, enable precision measurements of top quark properties and couplings as well as other electroweak precision measurements and provide extensive discovery potential for new physics co...

  10. Ion colliders

    International Nuclear Information System (INIS)

    Ion colliders are research tools for high-energy nuclear physics, and are used to test the theory of Quantum Chromo Dynamics (QCD). The collisions of fully stripped high-energy ions create matter of a temperature and density that existed only microseconds after the Big Bang. Ion colliders can reach higher densities and temperatures than fixed target experiments although at a much lower luminosity. The first ion collider was the CERN Intersecting Storage Ring (ISR), which collided light ions (77Asb1, 81Bou1). The BNL Relativistic Heavy Ion Collider (RHIC) is in operation since 2000 and has collided a number of species at numerous energies. The CERN Large Hadron Collider (LHC) started the heavy ion program in 2010. Table 1 shows all previous and the currently planned running modes for ISR, RHIC, and LHC. All three machines also collide protons, which are spin-polarized in RHIC. Ion colliders differ from proton or antiproton colliders in a number of ways: the preparation of the ions in the source and the pre-injector chain is limited by other effects than for protons; frequent changes in the collision energy and particle species, including asymmetric species, are typical; and the interaction of ions with each other and accelerator components is different from protons, which has implications for collision products, collimation, the beam dump, and intercepting instrumentation devices such a profile monitors. In the preparation for the collider use the charge state Z of the ions is successively increased to minimize the effects of space charge, intrabeam scattering (IBS), charge change effects (electron capture and stripping), and ion-impact desorption after beam loss. Low charge states reduce space charge, intrabeam scattering, and electron capture effects. High charge states reduce electron stripping, and make bending and acceleration more effective. Electron stripping at higher energies is generally more efficient. Table 2 shows the charge states and energies in the

  11. Implication of the Steady State Equilibrium Condition for Electron-Positron Gas in the Neutrino-driven Wind from Proto-Neutron Star

    CERN Document Server

    Liu, Men-Quan

    2010-01-01

    Based on the steady state equilibrium condition for neutron-proton-electron-positron gas in the neutrino-driven wind from protoneutron star, we estimate the initial electron fraction in the wind in a simple and effective way. We find that the condition in the wind might be propriate for the r-process nucleosynthesis.

  12. Observation of Exclusive Electron-Positron Production in Hadron-Hadron Collisions

    CERN Document Server

    Abulencia, A; Affolder, T; Akimoto, T; Albrow, M G; Ambrose, D; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arguin, J F; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Bedeschi, F; Behari, S; Belforte, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bölla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, Yu A; Budd, H S; Budd, S; Budroni, S; Burkett, K; Busetto, G; Bussey, P; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carillo, S; Carlsmith, D; Caron, B; Carosi, R; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciljak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca-Almenar, C; Cuevas-Maestro, J; Culbertson, R; Cully, J C; Cyr, D; Da Ronco, S; D'Auria, S; Davies, T; D'Onofrio, M; Dagenhart, D; De Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; Dell'Orso, Mauro; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; Di Turo, P; Dorr, C; Donati, S; Donega, M; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernández, J P; Field, R; Flanagan, G; Foland, A; Forrester, S; Foster, G W; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; García, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, A; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Gómez, G; Gómez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Griffiths, M; Grinstein, S; Grosso-Pilcher, C; Group, R C; Grundler, U; Guimarães da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Höcker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J R; Introzzi, G; Iori, M; Ishizawa, Y; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jensen, H; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kovalev, A; Kraan, A C; Kraus, J; Kravchenko, I; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Loverre, P F; Lu, R S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Mäki, T; Maksimovic, P; Malde, S; Manca, G; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtälä, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moore, R; Morello, M; Movilla-Fernández, P A; Mülmenstädt, J; Mukherjee, A; Müller, T; Mumford, R; Murat, P; Nachtman, J; Nagano, A; Naganoma, J; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nigmanov, T; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Österberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, Aldo L; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pinfold, J L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ranjan, N; Rappoccio, S; Reisert, B; Rekovic, V; Renton, P B; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Sabik, S; Safonov, A; Sakumoto, W K; Salamanna, G; Salto, O; Saltzberg, D; Sánchez, C; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shapiro, M D; Shears, T G; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakian, A; Sjölin, J; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Söderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; Saint-Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Takikawa, K; Tanaka, M; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuchiya, R; Tsuno, S; Turini, N; Ukegawa, F; Unverhau, T; Uozumi, S; Usynin, D; Vallecorsa, S; Van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Veramendi, G; Veszpremi, V; Vidal, R; Vila, I; Vilar, R; Vine, T; Vollrath, I; Volobuev, I P; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waschke, S; Waters, D; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S

    2006-01-01

    We present the first observation of exclusive $e^+e^-$ production in hadron-hadron collisions, using $p\\bar{p}$ collision data at \\mbox{$\\sqrt{s}=1.96$ TeV} taken by the Run II Collider Detector at Fermilab, and corresponding to an integrated luminosity of \\mbox{532 pb$^{-1}$}. We require the absence of any particle signatures in the detector except for an electron and a positron candidate, each with transverse energy {$E_T>5$ GeV} and pseudorapidity {$|\\eta|<2$}. With these criteria, 16 events are observed compared to a background expectation of {$1.9\\pm0.3$} events. These events are consistent in cross section and properties with the QED process \\mbox{$p\\bar{p} \\to p + e^+e^- + \\bar{p}$} through two-photon exchange. The measured cross section is \\mbox{$1.6^{+0.5}_{-0.3}\\mathrm{(stat)}\\pm0.3\\mathrm{(syst)}$ pb}. This agrees with the theoretical prediction of {$1.71 \\pm 0.01$ pb}.

  13. Measurement of the left-right asymmetry in Z boson production by electron-positron collisions

    International Nuclear Information System (INIS)

    We present the first measurement of the left-right cross-section asymmetry (ALR) in Z boson production at the SLAC Linear Collider. The left-right asymmetry provides a direct measurement of the e--Z coupling and thus of the effective weak mixing angle; in addition, ALR is sensitive to the unknown top-quark and Higgs-boson masses. In 1992 the SLD detector recorded 10224 Z events produced by the collision of longitudinally polarized electrons with an unpolarized positron beam at a center-of-mass energy of 91.55 GeV. The average electron beam polarization during the run was (22.4 ± 0.6)%. We measure ALR to be 0.101 ± 0.044 (stat.) ± 0.004 (syst.), which determines the effective weak mixing angle to be sin2 θeff/W = 0.2377 ± 0.0056 (stat.) ± 0.0005 (syst.). This measurement of ALR is in agreement with comparable measurements and is consistent with Standard-Model predictions for allowed top and Higgs masses

  14. Physics and technology of the next linear collider

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-06-01

    The authors present the prospects for the next generation of high-energy physics experiments with electron-positron colliding beams. This report summarizes the current status of the design and technological basis of a linear collider of center-of-mass energy 0.5--1.5 TeV, and the opportunities for high-energy physics experiments that this machine is expected to open. The physics goals discussed here are: Standard Model processes and simulation; top quark physics; Higgs boson searches and properties; supersymmetry; anomalous gauge boson couplings; strong WW scattering; new gauge bosons and exotic particles; e{sup {minus}}e{sup {minus}}, e{sup {minus}}{gamma}, and {gamma}{gamma} interactions; and precision tests of QCD.

  15. Physics and technology of the next linear collider

    International Nuclear Information System (INIS)

    The authors present the prospects for the next generation of high-energy physics experiments with electron-positron colliding beams. This report summarizes the current status of the design and technological basis of a linear collider of center-of-mass energy 0.5--1.5 TeV, and the opportunities for high-energy physics experiments that this machine is expected to open. The physics goals discussed here are: Standard Model processes and simulation; top quark physics; Higgs boson searches and properties; supersymmetry; anomalous gauge boson couplings; strong WW scattering; new gauge bosons and exotic particles; e-e-, e-γ, and γγ interactions; and precision tests of QCD

  16. Study of the electroweak electron (positron)-proton interactions at HERA

    International Nuclear Information System (INIS)

    The Standard Model of the Electroweak Theory can be tested at HERA, the electron-proton collider, through the study of the deep-inelastic ep scattering at the center of mass energy of about 300 GeV, complementary to the previous experiments by extending the kinematic domain to a region where the weak propagators of W and Z play a predominant role. This work presents an analysis on the charged current and the neutral current processes from the 1993 and 1994 electro(positron)-proton interaction data at HERA acquired by the H1 detector. We have measured the ratio between the integrated cross sections of the neutral current and the charged current processes, and the integrated charged current cross sections, with a cut at 25 GeV on the hadronic transverse momentum. The charged current and the neutral current events were selected in parallel, i.e. following the same vertex, trigger and technical requirements, and the background rejection cuts were applied to the NC and CC samples in the same way. The kinematic variables were calculated by only using information from the hadronic energy flow. We have also measured the differential cross sections as a function of the momentum transfer variable in four bins for both processes. The results agree well with the Standard Model predictions. The mass of the weak intermediate W boson implied by these results is also in good agreement with the previous measurements in other laboratories. The effect of the W-propagator in the deep inelastic charged current process is observed, for the first time, in these measurements. (author)

  17. Development and applications of super high energy collider accelerators. Vol. 1

    International Nuclear Information System (INIS)

    This paper presents a review of cyclic accelerators and their energy limitations. A description is given of the phase stability principle and evaluation of the synchrotron, an accelerator without energy limitation. Then the concept of colliding beams emerged to yield doubling of the beam energy as in the Tevatron 2 trillion electron volts (TeV) proton collider at Fermilab, and the large harden collider (LHD) which is now planned as a 14-TeV machine in the 27 Kilometer tunnel of the large electron positron (LEP) collider at CERN. Then presentation is given of the superconducting supercollider (SSC), a giant accelerator complex with energy 40-TeV in a tunnel 87 Kilometers in circumference under the country surrounding Waxahachile in Texas, U.S.A. These superhigh energy accelerators are intended to smash protons against protons at energy sufficient to reveal the nature of matter and to consolidate the prevailing general theory of elementary particles. 12 figs., 1 tab

  18. Risks and benefits of building the superconducting super collider. Special study

    International Nuclear Information System (INIS)

    Contents: introduction--what is the Superconducting Super Collider, current status of the SSC, evaluating the SSC; the SSC and the public interest--basic science and the public interest, the federal science portfolio, economies of scale in basic science, spinoffs from the SSC; budgetary risks in the SSC project--current DOE cost estimates for the SSC, overview of budgetary risks, detectors, superconducting magnets, conventional facilities, schedule, increases in construction costs of previous accelerators, sharing the cost of the SSC; congressional options--defer the decision, build the Superconducting Super Collider, join CERN in building the large hadron collider, build an electron-positron linear collider, build the SSC using high-temperature superconductors; appendixes--technology spinoffs from government programs, technology spinoffs from CERN accelerator research, cost increases in DOE accelerators

  19. Precise and fast beam energy measurement at the international linear collider

    Energy Technology Data Exchange (ETDEWEB)

    Viti, Michele

    2010-02-15

    The international Linear Collider (ILC) is an electron-positron collider with a center-of-mass energy between 200 and 500 GeV and a peak luminosity of 2 . 10{sup 34} cm{sup -2}s{sup -1}. For the physics program at this machine, an excellent bunch-by-bunch control of the beam energy is mandatory. Several techniques are foreseen to be implemented at the ILC in order to achieve this request. Energy spectrometers upstream and downstream of the electron/positron interaction point were proposed and the present default option for the upstream spectrometer is a beam position monitor based (BPM-based) spectrometer. In 2006/2007, a prototype of such a device was commissioned at the End Station A beam line at the Stanford Linear Accelerator Center (SLAC) in order to study performance and reliability. In addition, a novel method based on laser Compton backscattering has been proposed, since as proved at the Large Electron-Positron Collider (LEP) and the Stanford Linear Collider (SLC), complementary methods are necessary to cross-check the results of the BPM-based spectrometer. In this thesis, an overview of the experiment at End Station A is given, with emphasis on the performance of the magnets in the chicane and first energy resolution estimations. Also, the novel Compton backscattering method is discussed in details and found to be very promising. It has the potential to bring the beam energy resolution well below the requirement of {delta}E{sub b}/E{sub b}=10{sup -4}. (orig.)

  20. Possible Cryogenic Configurations for the Superconducting Magnets of the Damping Rings of the Compact Linear Collider (CLIC)

    CERN Document Server

    Perin, A; Russenschuck, S; Schoerling, D

    2012-01-01

    The Compact Linear Collider is a future electron-positron linear collider currently under study. Before being injected into the main linear accelerating structures, both the electron and the positron beams must pass through damping rings that will drastically reduce their emittance in all three dimensions. The required emittance reduction is achieved by passing the particle beams through alternating magnetic fields in superconducting wiggler magnets that result in the emission of intense synchrotron radiation. This article describes possible cooling schemes and possible cryogenic configurations to keep the magnets at operating temperature while removing the heat generated by the synchrotron radiation.

  1. Future colliders

    International Nuclear Information System (INIS)

    The high energy physics advantages, disadvantages and luminosity requirements of hadron (pp, pp), of lepton (e+e-, μ+ μ-) and photon-photon colliders are considered. Technical arguments for increased energy in each type of machine are presented. Their relative size, and the implications of size on cost are discussed

  2. Linear colliders

    International Nuclear Information System (INIS)

    From November 28 to December 9, the Stanford Linear Accelerator Center hosted an International Workshop on Next Generation Linear Colliders. The attendance, including delegations from CERN, Frascati (Italy), KEK (Japan), Livermore (US), Novosibirsk (USSR), Drsay (France) and SLAC itself reflected the international interest in this new approach to higher energies

  3. Prospects for very-high-gradient linac-colliders

    International Nuclear Information System (INIS)

    The energy realistically attainable by an electron-positron storage ring is limited by the RF voltage and power requirements imposed by synchrotron radiation to about 100 GeV. To reach energies of 300 x 300 GeV and higher in a colliding beam machine of reasonable dimensions, we must look to the linac-collider operating at an energy gradient on the order of 100 MV/m. Proper choice of an RF structure or such a collider can minimize the total RF power requirement and the effects of longitudinal and transverse single-bunch beam loading. For an operating frequency in the range 4 to 6 GHz, the total RF power requirement for a 300 x 300 GeV collider with a luminosity of 1032 cm-2s-1 accelerating 1011 particles per bunch is on the order of 50 MW. To drive this collider, RF power sources are needed having a peak output power in the range 1-2 GW. Possibilities for attaining these peak power levels by direct generation and by energy storage and fast switching are discussed

  4. 1999 Beijing Music Festival

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    THE Beijing Music Festival has been a labour of love for conductor Yu Long since he began the event in 1998. For Beijing, the ancient capital of China, to have its own music festival on the international level, has been the long cherished wish of Yu Long, chief organizer of the Beijing Music Festival. In recent years he settled in Hong Kong and worked as the conductor of many excellent philharmonic orchestras from

  5. Marketing report: Beijing 2008

    OpenAIRE

    2012-01-01

    The Beijing 2008 Olympic Games Marketing Report provides a comprehensive summary of the Beijing 2008 marketing programmes, which made such a significant contribution to the exceptional success of the Games. Highlighted throughout the publication are the contributions, efforts and inter-dependencies of the many stakeholders in the Olympic Movement, on which the modern Olympic Games are built. Beijing delivered great Games because it delivered in every area – record sporting achievements, super...

  6. INTERCONTINENTAL FINANCIAL STREET BEIJING

    Institute of Scientific and Technical Information of China (English)

    ZHANGCHUNYUE; FENGJIAYUN

    2005-01-01

    InterContinental Financial Street Beijing opened its doors on May 1st, 2005, just days before the world's business leaders flooded into town for the Fortune Global Forum.The first international luxury hotel in the Chinese capital's new and rapidly growing Financial Street business center, the InterContinental Financial Street Beijing is the flagship property of FnterContinental Hotels and Resorts on the Chinese mainland, and as such a pioneer in Beijing's future,

  7. Amplitude modulation of quantum-ion-acoustic wavepackets in electron-positron-ion plasmas: Modulational instability, envelope modes, extreme waves

    International Nuclear Information System (INIS)

    A semirelativistic fluid model is employed to describe the nonlinear amplitude modulation of low-frequency (ionic scale) electrostatic waves in an unmagnetized electron-positron-ion plasma. Electrons and positrons are assumed to be degenerated and inertialess, whereas ions are warm and classical. A multiscale perturbation method is used to derive a nonlinear Schrödinger equation for the envelope amplitude, based on which the occurrence of modulational instability is investigated in detail. Various types of localized ion acoustic excitations are shown to exist, in the form of either bright type envelope solitons (envelope pulses) or dark-type envelope solitons (voids, holes). The plasma configurational parameters (namely, the relativistic degeneracy parameter, the positron concentration, and the ionic temperature) are shown to affect the conditions for modulational instability significantly, in fact modifying the associated threshold as well as the instability growth rate. In particular, the relativistic degeneracy parameter leads to an enhancement of the modulational instability mechanism. Furthermore, the effect of different relevant plasma parameters on the characteristics (amplitude, width) of these envelope solitary structures is also presented in detail. Finally, the occurrence of extreme amplitude excitation (rogue waves) is also discussed briefly. Our results aim at elucidating the formation and dynamics of nonlinear electrostatic excitations in superdense astrophysical regimes

  8. Impacts of B-factory measurements on determination of fragmentation functions from electron-positron annihilation data

    CERN Document Server

    Hirai, M; Kumano, S; Saito, K

    2016-01-01

    Fragmentation functions are determined for the pion and kaon by global analyses of charged-hadron production data in electron-positron annihilation. Accurate measurements were reported by the Belle and BaBar collaborations for the fragmentation functions at the center-of-mass energies of 10.52 GeV and 10.54 GeV, respectively, at the KEK and SLAC B factories, whereas other available $e^+e^-$ measurements were mostly done at higher energies, mainly at the $Z$ mass of 91.2 GeV. There is a possibility that gluon fragmentation functions, as well as quark fragmentation functions, are accurately determined by scaling violation. We report our global analysis of the fragmentation functions especially to show impacts of the B-factory measurements on the fragmentation function determination. Our results indicate that the fragmentation functions are determined more accurately not only by the scaling violation but also by high-statistical nature of the Belle and BaBar data. However, there are some tensions between the Bel...

  9. Kinetic transverse dispersion relation for relativistic magnetized electron-positron plasmas with Maxwell-Jüttner velocity distribution functions

    International Nuclear Information System (INIS)

    We use a kinetic treatment to study the linear transverse dispersion relation for a magnetized isotropic relativistic electron-positron plasma with finite relativistic temperature. The explicit linear dispersion relation for electromagnetic waves propagating along a constant background magnetic field is presented, including an analytical continuation to the whole complex frequency plane for the case of Maxwell-Jüttner velocity distribution functions. This dispersion relation is studied numerically for various temperatures. For left-handed solutions, the system presents two branches, the electromagnetic ordinary mode and the Alfvén mode. In the low frequency regime, the Alfvén branch has two dispersive zones, the normal zone (where ∂ω/∂k > 0) and an anomalous zone (where ∂ω/∂k < 0). We find that in the anomalous zone of the Alfvén branch, the electromagnetic waves are damped, and there is a maximum wave number for which the Alfvén branch is suppressed. We also study the dependence of the Alfvén velocity and effective plasma frequency with the temperature. We complemented the analytical and numerical approaches with relativistic full particle simulations, which consistently agree with the analytical results

  10. Kinetic transverse dispersion relation for relativistic magnetized electron-positron plasmas with Maxwell-Jüttner velocity distribution functions

    Energy Technology Data Exchange (ETDEWEB)

    López, Rodrigo A. [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción (Chile); Moya, Pablo S. [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, Maryland 20771 (United States); Department of Physics, Catholic University of America, Washington DC, DC 20064 (United States); Muñoz, Víctor [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Viñas, Adolfo F. [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, Maryland 20771 (United States); Valdivia, J. Alejandro [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Santiago (Chile)

    2014-09-15

    We use a kinetic treatment to study the linear transverse dispersion relation for a magnetized isotropic relativistic electron-positron plasma with finite relativistic temperature. The explicit linear dispersion relation for electromagnetic waves propagating along a constant background magnetic field is presented, including an analytical continuation to the whole complex frequency plane for the case of Maxwell-Jüttner velocity distribution functions. This dispersion relation is studied numerically for various temperatures. For left-handed solutions, the system presents two branches, the electromagnetic ordinary mode and the Alfvén mode. In the low frequency regime, the Alfvén branch has two dispersive zones, the normal zone (where ∂ω/∂k > 0) and an anomalous zone (where ∂ω/∂k < 0). We find that in the anomalous zone of the Alfvén branch, the electromagnetic waves are damped, and there is a maximum wave number for which the Alfvén branch is suppressed. We also study the dependence of the Alfvén velocity and effective plasma frequency with the temperature. We complemented the analytical and numerical approaches with relativistic full particle simulations, which consistently agree with the analytical results.

  11. Massless states and negative mass states of the coupled electron-positron system with completely symmetric representation of the particles

    CERN Document Server

    Agafonov, A I

    2016-01-01

    We argue that the free electron and positron can be considered as different, independent particles, each of which is characterized by the complete set of the Dirac plane waves. This completely symmetric representation of the particles makes it necessary to choose another solution of the Dirac equation for the free particle propagator as compared to that currently used in QED. Studying the Bethe-Salpeter equation in the ladder approximation with these free propagators, two new branches of electron-positron bound states which represent the composite bosons, have been found. The first branch corresponds to the negative mass boson whose mass is approximately equal to $-2m$ . These bound states have certain symmetry with respect to the Ps states. For the radiative transition from the Ps states into the negative mass boson states the total energy of the generated gamma quanta should be approximately equal to $4m$. The second branch describes the massless bosons which have been found for the real coupling equal to t...

  12. Towards an accurate representation of the continuum in calculations of electron, positron and laser field interactions with molecules

    International Nuclear Information System (INIS)

    Gaussian-type orbitals (GTOs) are the most common choice of basis functions in calculations of electronic structure of molecules, i.e. for the description of bound electrons. The main advantage of this approach is the analytic form of the multicentre molecular integrals. For the same reason GTOs have been adopted as basis functions for the description of the unbound particle in many ab-initio calculations of electron, positron and laser fields interacting with molecules. However, the accurate description of the unbound particle using GTOs may become very difficult and in some cases numerically unstable. We describe an approach for the representation of the continuum in which the unbound particle is described using a mixed GTO and B-spline basis set in a manner which exploits the best features of these functions. Analytical expressions for the GTO-only molecular integrals allow us to accurately represent the part of the wavefunction close to the target, while the B-splines enable us to represent accurately the wavefunction's tail, corresponding to the unbound particle, over a wide range of kinetic energies. The main challenge posed by this approach is the accurate and rapid numerical evaluation of a large number of mixed BTO/GTO molecular integrals. We propose a scheme for this integral calculation in which the overlap integrals between GTOs and B-spline functions play a central role and demonstrate that they can be calculated rapidly and accurately

  13. On Possible Interpretations of the High Energy Electron-Positron Spectrum Measured by the Fermi Large Area Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Grasso, D.; Profumo, S.; Strong, A.W.; Baldini, L.; Bellazzini, R.; Bloom, E.D.; Bregeon, J.; Di Bernardo, G.; Gaggero, D.; Giglietto, N.; Kamae, T.; Latronico, L.; Longo, F.; Mazziotta, M.N.; Moiseev, A.A.; Morselli, A.; Ormes, J.F.; Pesce-Rollins, M.; Pohl, M.; Razzano, M.; Sgro, C.

    2009-05-15

    The Fermi-LAT experiment recently reported high precision measurements of the spectrum of cosmic-ray electrons-plus-positrons (CRE) between 20 GeV and 1 TeV. The spectrum shows no prominent spectral features, and is significantly harder than that inferred from several previous experiments. Here we discuss several interpretations of the Fermi results based either on a single large scale Galactic CRE component or by invoking additional electron-positron primary sources, e.g. nearby pulsars or particle Dark Matter annihilation. We show that while the reported Fermi-LAT data alone can be interpreted in terms of a single component scenario, when combined with other complementary experimental results, specifically the CRE spectrum measured by H.E.S.S. and especially the positron fraction reported by PAMELA between 1 and 100 GeV, that class of models fails to provide a consistent interpretation. Rather, we find that several combinations of parameters, involving both the pulsar and dark matter scenarios, allow a consistent description of those results. We also briefly discuss the possibility of discriminating between the pulsar and dark matter interpretations by looking for a possible anisotropy in the CRE flux.

  14. Amplitude modulation of quantum-ion-acoustic wavepackets in electron-positron-ion plasmas: Modulational instability, envelope modes, extreme waves

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Ata-ur-, E-mail: ata797@yahoo.com [Department of Physics, University of Peshawar, Peshawar 25000 (Pakistan); Department of Physics, Islamia College Peshawar, Khyber Pakhtunkhwa (Pakistan); Kerr, Michael Mc, E-mail: mjamckerr@gmail.com; Kourakis, Ioannis, E-mail: IoannisKourakisSci@gmail.com [Centre for Plasma Physics, Department of Physics and Astronomy, Queen' s University Belfast, BT7 1NN Northern Ireland (United Kingdom); El-Taibany, Wael F., E-mail: eltaibany@hotmail.com [Department of Physics, Faculty of Science, Damietta University, New Damietta, P.O. Box 34517 (Egypt); Department of Physics, College of Science for Girls in Abha, King Khalid University, P.O. Box 960, Abha (Saudi Arabia); Qamar, A., E-mail: anisaqamar@gmail.com [Department of Physics, University of Peshawar, Peshawar 25000 (Pakistan)

    2015-02-15

    A semirelativistic fluid model is employed to describe the nonlinear amplitude modulation of low-frequency (ionic scale) electrostatic waves in an unmagnetized electron-positron-ion plasma. Electrons and positrons are assumed to be degenerated and inertialess, whereas ions are warm and classical. A multiscale perturbation method is used to derive a nonlinear Schrödinger equation for the envelope amplitude, based on which the occurrence of modulational instability is investigated in detail. Various types of localized ion acoustic excitations are shown to exist, in the form of either bright type envelope solitons (envelope pulses) or dark-type envelope solitons (voids, holes). The plasma configurational parameters (namely, the relativistic degeneracy parameter, the positron concentration, and the ionic temperature) are shown to affect the conditions for modulational instability significantly, in fact modifying the associated threshold as well as the instability growth rate. In particular, the relativistic degeneracy parameter leads to an enhancement of the modulational instability mechanism. Furthermore, the effect of different relevant plasma parameters on the characteristics (amplitude, width) of these envelope solitary structures is also presented in detail. Finally, the occurrence of extreme amplitude excitation (rogue waves) is also discussed briefly. Our results aim at elucidating the formation and dynamics of nonlinear electrostatic excitations in superdense astrophysical regimes.

  15. Fully self-consistent calculations of momentum distributions of annihilating electron-positron pairs in SiC

    Science.gov (United States)

    Wiktor, Julia; Jomard, Gérald; Torrent, Marc; Barthe, Marie-France; Bertolus, Marjorie

    2016-05-01

    We performed calculations of momentum distributions of annihilating electron-positron pairs in various fully relaxed vacancy defects in SiC. We used self-consistent two-component density functional theory schemes to find the electronic and positronic densities and wave functions in the considered systems. Using the one-dimensional momentum distributions (Doppler-broadened annihilation radiation line shapes) we calculated the line-shape parameters S and W . We emphasize the effect of the experimental resolution and the choice of the integration ranges for the S and W parameters on the distributions of the points corresponding to different defects in the S (W ) plot. We performed calculation for two polytypes of SiC, 3 C , and 6 H and showed that for silicon vacancies and clusters containing this defect there were no significant differences between the Doppler spectra. The results of the Doppler spectra calculations were compared with experimental data obtained for n -type 6 H -SiC samples irradiated with 4-MeV Au ions. We observed a good general agreement between the measured and calculated points.

  16. Comparison of single-electron removal processes in collisions of electrons, positrons, protons, and antiprotons with hydrogen and helium

    International Nuclear Information System (INIS)

    We present and compare total cross sections for single-electron removal in collisions of electrons, positrons, protons, and antiprotons with atomic hydrogen and helium. These cross sections have been calculated using the classical trajectory Monte Carlo technique in the velocity range of 0.5--7.0 a.u. (6.25--1224 keV/u). The cross sections are compared at equal collision velocities and exhibit differences arising from variations in mass and sign of charge of the projectile. At low and intermediate velocities these differences are large in both the ionization and charge transfer channels. At high velocities the single-ionization cross section for each of these singly charged particles becomes equal. However, the differences in the single-charge-transfer cross sections for positron and proton impact persist to very large velocities. We extend our previous work [Phys. Rev. A 38, 1866 (1988)] to explain these mass and sign of the charge effects in single-electron removal collisions

  17. The Large Hadron Collider, a personal recollection

    CERN Document Server

    Evans, L

    2014-01-01

    The construction of the Large Hadron Collider (LHC) has been a massive endeavor spanning almost 30 years from conception to commissioning. Building the machine with the highest possible energy (7 TeV) in the existing LEP tunnel of 27 km circumference and with a tunnel diameter of only 3.8m has required considerable innovation. The first was the development of an idea first proposed by Bob Palmer at Brookhaven National Laboratory in 1978, where the two rings are integrated into a single magnetic structure. This compact 2-in-1 structure was essential for the LHC due to both the limited space available in the existing Large Electron-Positron collider tunnel and the cost. The second innovation was the bold move to use superfluid helium cooling on a massive scale, which was imposed by the need to achieve a high (8.3 T) magnetic field using an affordable Nb-Ti superconductor. In this article, no attempt is made to give a comprehensive review of the machine design. This can be found in the LHC Design Report {[}1], w...

  18. German lab wins linear collider contest

    CERN Multimedia

    Cartlidge, Edwin

    2004-01-01

    Particle physicists have chosen to base the proposed International Linear Collider on superconducting technology developed by an international collaboration centred on the DESY lab in Germany. The superconducting approach was chosen by an internatinal panel ahead of a rival technology developed at Stanford in the US and the KEK lab in Japan. The eagerly-awaited decision was announced at the International Conference on High Energy Physics in Beijing today (½ page)

  19. Study of the performance of a compact sandwich calorimeter for the instrumentation of the very forward region of a future linear collider detector

    OpenAIRE

    Ghenescu, V.; Benhammou, Y.

    2016-01-01

    The FCAL collaboration is preparing large scale prototypes of special calorimeters to be used in the very forward region at a future linear electron positron collider for a precise and fast luminosity measurement and beam-tuning. These calorimeters are designed as sensor-tungsten calorimeters with very thin sensor planes to keep the Moliere radius small and dedicated FE electronics to match the timing and dynamic range requirements. A partially instrumented prototype was investigated in the C...

  20. NEUTRINO RADIATION CHALLENGES AND PROPOSED SOLUTIONS FOR MANY-TEV MUON COLLIDERS

    International Nuclear Information System (INIS)

    Neutrino radiation is expected to impose major design and siting constraints on many-TeV muon colliders. Previous predictions for radiation doses at TeV energy scales are briefly reviewed and then modified for extension to the many-TeV energy regime. The energy-cubed dependence of lower energy colliders is found to soften to an increase of slightly less than quadratic when averaged over the plane of the collider ring and slightly less than linear for the radiation hot spots downstream from straight sections in the collider ring. Despite this, the numerical values are judged to be sufficiently high that any many-TeV muon colliders will likely be constructed on large isolated sites specifically chosen to minimize or eliminate human exposure to the neutrino radiation. It is pointed out that such sites would be of an appropriate size scale to also house future proton-proton and electron-positron colliders at the high energy frontier, which naturally leads to conjecture on the possibilities for a new world laboratory for high energy physics. Radiation dose predictions are also presented for the speculative possibility of linear muon colliders. These have greatly reduced radiation constraints relative to circular muon colliders because radiation is only emitted in two pencil beams directed along the axes of the opposing linacs

  1. Extracting X rays, gamma rays, and electron-positron pairs from supermassive Kerr black holes using the Penrose mechanism

    Science.gov (United States)

    Williams, Reva Kay D.

    Monte Carlo computer simulations are presented of Compton scattering and electron-positron (e-e+) pair production processes in the ergosphere of a supermassive rotating black hole. Particles from an accretion disk surrounding the black hole fall into the ergosphere and scatter off particles that are in bound orbits. The equations that govern the orbital trajectory of a particle about a Kerr (rotating) black hole (KBH) are solved to determine the conserved energy and angular momentum of materials and massless particles that have orbits not confined to the equatorial plane. The escape conditions to determine whether or not a particle escapes from the potential well of the KBH are applied to the scatter particles. The Penrose mechanism allows rotational energy of a KBH to be extracted by scattered particles escaping from the ergosphere to large distances from the black hole. The results of these model calculations show that the Penrose mechanism is capable of producing the astronomically observed high energy particles emitted by quasars and other active galactic nuclei (AGN's). This mechanism, as applied in the models, can extract hard X ray/gamma ray photons from the inverse Compton scatterings of initially low energy UV/soft X ray photons by target orbiting electrons in the ergosphere. Such low energy infalling photons are consistent with photons emitted by of a classical thin accretion disk. These model calculations also allow relativistic e-e+ pairs to be produced by infalling low energy photons interacting with target photons in bound orbits inside the ergosphere. This process may be the origin of the relativistic electrons inferred from observations to emerge from the cores of AGN's.

  2. SUMMARY OF SNOWMASS ACCELERATOR GROUP M2 ON E+ E- CIRCULAR COLLIDERS

    International Nuclear Information System (INIS)

    Perform a survey of the present status as well as the vision of the future promises of the various electron-positron circular colliders. The colliders to be covered include those currently in operation, currently under construction, or envisioned as a possibility of the future, and in the US and abroad. Special emphasis should be placed on the clear identification of the beam physics limits and technological limits, and an examination of the extent that they have been address by past research or need to be addressed by future research. Identify new and promising ideas even though they may need additional work. These issues should be addressed for all the leading technical realizations of the circular positron-electron colliders. Finally, the group should summarize in a brief report the highest priority research topics for different technological realizations of circular electron-positron systems and give an approximate timetable for key R and D development [1]. The group is also asked to provide a comprehensive presentation to high-energy and accelerator physicists in plenary sessions during the Snowmass workshop

  3. A Silicon-Tungsten Electromagnetic Calorimeter with Integrated Electronics for the International Linear Collider

    Science.gov (United States)

    Brau, J.; Breidenbach, M.; Frey, R.; Freytag, D.; Gallagher, C.; Graf, N.; Haller, G.; Herbst, R.; Holbrook, B.; Jaros, J.; Lander, R.; Radloff, P.; Strom, D.; Tripathi, M.; Woods, M.

    2012-12-01

    We present an update of the development of an electromagnetic calorimeter for the Silicon Detector concept for a future linear electron-positron collider. After reviewing the design criteria and related simulation studies, we discuss progress in the research and development of the detector. This concept has from the outset made the case for highly integrated electronic readout with small (1 mm) readout gaps in order to maintain a small Moliere radius for electromagnetic showers and to avoid active heat removal. We now have fully functioning 1024-channel readout chips which have been successfully bonded to 15 cm silicon sensors. We present initial results from these assemblies.

  4. Multivariate Methods For Hadronic Final States In Electron-positron Collisions At Center Of Mass Energy = 500 Gev

    CERN Document Server

    Pathak, S

    2005-01-01

    We approach the hadronic final state events in a future linear collider at s = 500 GeV from the knowledge discovery (data mining) point of view. We present FastCal, a fast configurable calorimeter Monte Carlo simulator for linear collider detector simulations that produces data at a rate that is 3000 times that of full simulation. Neural networks based on earlystopping are designed for the jet- combinatorial problem. CJNN, a neural network package is presented for use in the linear collider analysis environment. Neural network performances are optimized by implementing an ensemble of neural networks. A binary tree is used to obtain novel automatic cuts on physics variables. Data visualization is introduced as a crucial component of data analysis, and principal component analysis is used to understand data distributions and structures in multiple dimensions. Finally, cluster analyses with fuzzy c-means and demographic clustering are used to partition data automatically in an unsupervised regime, and we sho...

  5. Probing the fermionic Higgs portal at lepton colliders

    CERN Document Server

    Fedderke, Michael A; Wang, Lian-Tao

    2015-01-01

    We study the sensitivity of future electron-positron colliders to UV completions of the fermionic Higgs portal operator $H^\\dagger H \\bar \\chi \\chi$. Measurements of precision electroweak $S$ and $T$ parameters and the $e^+e^- \\to Zh$ cross section at the CEPC, FCC-ee, and ILC are considered. The scalar completion of the fermionic Higgs portal is closely related to the scalar Higgs portal, and we summarize existing results. We devote the bulk of our analysis to a singlet-doublet fermion completion. Assuming the doublet is sufficiently heavy, we construct the effective field theory (EFT) at dimension-6 in order to compute contributions to the observables. We also provide full one-loop results for $S$ and $T$ in the general mass parameter space. In both completions, future precision measurements can probe the new states at the (multi-)TeV scale, beyond the direct reach of the LHC.

  6. Enhanced creation of high energy particles in colliding laser beams

    CERN Document Server

    Kuchiev, Michael

    2015-01-01

    The creation of particles by two colliding strong laser beams is considered. It is found that the electron-positron pairs created in the laser field via the Schwinger mechanism may recollide after one or several oscillations in the field. Their collision can take place at high energy, which the pair gains from the field. As a result, high energy gamma quanta can be created by inelastic scattering or annihilation of the pair. Moreover, heavy particles such as muon pairs may also be created via the annihilation $e^+ + e^-\\rightarrow \\mu^+ + \\mu^- $. The probability of $e^-e^+$ collision is greatly enhanced due to a strong alignment of the electron and positron momenta with the electric field. The found muon creation rate exponentially exceeds the rate predicted by the direct Schwinger mechanism for muons, while the photon creation rate exponentially exceeds photon emission due to the fermion oscillation.

  7. Probing the fermionic Higgs portal at lepton colliders

    Science.gov (United States)

    Fedderke, Michael A.; Lin, Tongyan; Wang, Lian-Tao

    2016-04-01

    We study the sensitivity of future electron-positron colliders to UV completions of the fermionic Higgs portal operator {H}^{dagger }{H}_{overline{χ}χ } . Measurements of precision electroweak S and T parameters and the e + e - → Zh cross-section at the CEPC, FCC-ee, and ILC are considered. The scalar completion of the fermionic Higgs portal is closely related to the scalar Higgs portal, and we summarize existing results. We devote the bulk of our analysis to a singlet-doublet fermion completion. Assuming the doublet is sufficiently heavy, we construct the effective field theory (EFT) at dimension-6 in order to compute contributions to the observables. We also provide full one-loop results for S and T in the general mass parameter space. In both completions, future precision measurements can probe the new states at the (multi-)TeV scale, beyond the direct reach of the LHC.

  8. Quasi-Optical Components for Future Linear Colliders

    CERN Document Server

    Kuzikov, S; Shmelyov, M Yu

    2004-01-01

    This paper presents a concept of the quasi-optical RF system for future Ka-band electron-positron linear collider. According to this concept two RF feeding systems are considered: a Delay Line Distribution System (DLDS) and a pulse compressor based on the multi-mirror traveling-wave resonator. The DLDS is based on oversized waveguides. In such waveguides the so-called image multiplication phenomena are used for power launching, extracting, combining, and splitting of waves. Recent low power tests of mode launchers and other DLDS components are discussed. The 34 GHz pulse compressors, based on three and four-mirror resonators, are considered. The tests of the prototypes at a low power level under different modulation methods are discussed. The simulations and tests of mode converters, miter bends, RF loads, and other components, to be necessary for both compression systems, also are resulted.

  9. Study of the electron-positron annihilation in the galactic center region with the Integral/SPI spectrometer

    International Nuclear Information System (INIS)

    A spectral feature was detected in 1970 in the gamma-ray emission from the central regions of the Milky Way, during balloon flight observations. Located near 511 keV, this feature was soon attributed to the gamma-ray line tracing the annihilation of electrons with their anti-particles, positrons. However, none of the multiple astrophysical scenarios contemplated to explain the production of positrons in the Galactic bulge has been able to reproduce the high injection rate deduced from the flux of the 511 keV line, close to 1043 positrons per second. Launched in 2002, the European gamma-ray satellite INTEGRAL was provided with a spectrometer, SPI, whose unprecedented imaging and spectral capabilities in this energy range enable us to further study the source of the 511 keV line detected in the Galactic centre region. Indeed, a better determination of the spatial extent of the source, the intrinsic width of the line and the fraction of positrons annihilating in-flight, directly or via the formation of ortho-Positronium atoms would improve our knowledge of both the annihilation medium and the initial source of positrons, and could allow us to discriminate between the various explanatory scenarios. The first part of this thesis deals with a key ingredient in the extraction of the annihilation spectrum: the optimization of the instrumental background model. New data screening and tracer selection procedures are presented. Classical multi-linear models are compared to neural and Bayesian networks. Finally, three years of observation are used to constrain the width of the source and derive its spectrum. The second part of the thesis focuses on one of the possible scenarios explaining the high positron injection rate deduced from the flux of the 511 keV line: the annihilation of light dark matter particles into electron-positron pairs. The various radiation mechanisms involved are modeled and confronted to observations in order to set an upper limit on the injection energy

  10. Beijing International Sculpture Park

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Inauguration of the 2002 Beijing International Urban Sculptural Art Exhibition also saw the opening of the Beijing International Sculpture Park on Yuquan Road, Beijing. The park houses 140 statues.This exhibition is aimed at promoting exchanges and cooperation among sculptors across the world, integrating urban sculpture into everyday life, and encouraging innovation in this sector. It is expected to bring inspiration to Beijing as regards new concepts in urban construction, through exchanges with other nations. This exhibition constitutes interaction between the public and art, and dialogue between China and the world.The works on display are Beijing’s latest attraction, and add a touch of modernity to this ancient city. Some are to be placed in sports stadiums during the 2008 Olympics.

  11. Developing the Beijing CVD

    Institute of Scientific and Technical Information of China (English)

    LU JINGXIAN

    2006-01-01

    @@ Slowly but surely, the high-end villa property in Beijing is gaining new momentum. Limited amounts of new properties, rising prices and increasing demand will be the trend in the villa market in 2006, real estate experts predict. Among them, the exclusive Central Villa District(CVD), a top-tier villa area along the Wenyu River in northeast Beijing, has emerged as a hot spot of the market.

  12. Dense electron-positron plasmas and gamma-ray bursts generation by counter-propagating quantum electrodynamics-strong laser interaction with solid targets

    International Nuclear Information System (INIS)

    We use quantum electrodynamics (QED) particle-in-cell simulations to investigate and compare the generation of dense electron-positron plasmas and intense γ-ray bursts in the case of counter-propagating laser solid interaction (two-side irradiation) and single laser solid interaction (one-side irradiation). In the case of counter-propagating linearly polarized laser pulses irradiating a thin aluminum foil with each pulse peak power of 12.5 PW (I = 4 × 1023 W/cm2), we calculate that about 20% of the laser energy is converted into a burst of γ-rays with flux exceeding 1014 s.−1 This would be one of the most intense γ-ray sources among those currently available in laboratories. The γ-ray conversion efficiency in the case of two-side irradiation is three times higher than in the case of one-side irradiation using a single 12.5 PW laser. Dense electron-positron plasma with a maximum density of 6 × 1027 m−3 are generated simultaneously during the two-side irradiation which is eightfold denser compared to the one-side irradiation. The enhancement of the effects in the case of counter-propagating lasers are the results of the symmetrical compression of the foil target and the formation of electric potential and standing wave around the target. Realizing experimentally the proposed counter-propagating QED-strong laser-solid interaction to produce dense electron-positron pairs and prolific γ-rays will be made possible by the Extreme Light Infrastructure-Nuclear Physics facility under construction

  13. Influence of anomalous thresholds in electron-positron annihilation into hadrons: the e+e- → rhoππ cross section

    International Nuclear Information System (INIS)

    We calculate the cross section for e+e- → rhoππ on the basis of partial-wave dispersion relations in the ππ channel taking proper account of anomalous singularity contributions. The appearance of anomalous thresholds is due to the fact that the vertex γsub(ν)rho(ππ) becomes internally unstable as the virtual photon mass is increased. Reasonable agreement with existing data is found. The anomalous singularity contributions provide by far the dominant part of the cross section which is a warning to using naive vector dominance extrapolations in estimating the electron-positron cross section. (orig.)

  14. Electron-positron momentum density distribution of Gd from 2D ACAR data via maximum entropy and Cormack's methods

    Energy Technology Data Exchange (ETDEWEB)

    Pylak, M. [Andrzej Soltan Institute for Nuclear Studies, Otwock-Swierk (Poland); Kontrym-Sznajd, G. [Polish Academy of Sciences, Institute of Low Temperature and Structure Research, P.O. Box 937, Wroclaw 2 (Poland); Dobrzynski, L. [Andrzej Soltan Institute for Nuclear Studies, Otwock-Swierk (Poland); University of Bialystok, Faculty of Physics, Bialystok (Poland)

    2011-08-15

    A successful application of the maximum entropy method (MEM) to the reconstruction of electron-positron momentum density distribution in gadolinium out of the experimental of 2D ACAR data is presented. Formally, the algorithm used was prepared for two-dimensional reconstructions from line integrals. For the first time the results of MEM, applied to such data, are compared in detail with the ones obtained by means of Cormack's method. It is also shown how the experimental uncertainties may influence the results of the latter analysis. Preliminary calculations, using WIEN2k code, of band structure and Fermi surface have been done as well. (orig.)

  15. Dark matter mini-halo around the compact objects: the formation, evolution and possible contribution to the cosmic ray electrons/positrons

    International Nuclear Information System (INIS)

    Dark matter particles may be captured by a star and then thermalized in the star's core. At the end of its life a massive star collapses suddenly and a compact object is formed. The dark matter particles redistribute accordingly. In the inelastic dark matter model, an extended dense dark matter mini-halo surrounding the neutron star may be formed. Such mini-halos may be common in the Galaxy. The electron/positron flux resulting in the annihilation of dark matter particles, however, is unable to give rise to observable signal unless a nascent mini-halo is within a distance ∼ a few 0.1 pc from the Earth

  16. Measurement of the Z boson differential cross-section in transverse momentum in the electron-positron channel with the ATLAS detector at LHC.

    OpenAIRE

    Martinez, Homero

    2013-01-01

    This work presents the measurement of the Z boson differential cross section in transverse momentum (ptz), in the electron-positron decay channel, using the ATLAS detector at the LHC. The measurement is done using 4.64 inverse fb of proton-proton collision data, collected in 2011 at a center-of-mass energy of 7 TeV. The result is combined with an independent measurement done in the muon-antimuon decay channel. The measurement is done up to ptz = 800 GeV, and has a typical uncertainty of 0.5 %...

  17. Neutrino Signals from Annihilating/Decaying Dark Matter in the Light of Recent Measurements of Cosmic Ray Electron/Positron Fluxes

    OpenAIRE

    Hisano, Junji; Kawasaki, Masahiro; Kohri, Kazunori; Nakayama, Kazunori

    2008-01-01

    The excess of cosmic-ray electron and positron fluxes measured by the PAMELA satellite and ATIC balloon experiments may be interpreted as the signals of the dark matter annihilation or decay into leptons. In this letter we show that the dark matter annihilation/decay which reproduces the electron/positron excess may yield a significant amount of high-energy neutrinos from the Galactic center. In the case, future kilometer-square size experiments may confirm such a scenario, or even the Super-...

  18. Measurement of the forward-backward asymmetry of Z boson decays in electron-positron pairs with the ATLAS detector in proton-proton collisions at √(s)=7 TeV at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, Sebastian

    2014-02-12

    In this thesis the measurement of the effective weak mixing angle sin{sup 2}θ{sub W}{sup eff} in proton-proton collisions is described. The results are extracted from the forward-backward asymmetry (A{sub FB}) in electron-positron final states at the ATLAS experiment at the LHC. The A{sub FB} is defined upon the distribution of the polar angle between the incoming quark and outgoing lepton. The signal process used in this study is the reaction pp→ Z/γ{sup *}+X→e{sup +}e{sup -}+X taking a total integrated luminosity of 4.8 fb{sup -1} of data into account. The data was recorded at a proton-proton center-of-mass energy of √(s)=7 TeV. The weak mixing angle is a central parameter of the electroweak theory of the Standard Model (SM) and relates the neutral current interactions of electromagnetism and weak force. The higher order corrections on sin{sup 2}θ{sub W}{sup eff} are related to other SM parameters like the mass of the Higgs boson. Because of the symmetric initial state constellation of colliding protons, there is no favoured forward or backward direction in the experimental setup. The reference axis used in the definition of the polar angle is therefore chosen with respect to the longitudinal boost of the electron-positron final state. This leads to events with low absolute rapidity have a higher chance of being assigned to the opposite direction of the reference axis. This effect called dilution is reduced when events at higher rapidities are used. It can be studied including electrons and positrons in the forward regions of the ATLAS calorimeters. Electrons and positrons are further referred to as electrons. To include the electrons from the forward region, the energy calibration for the forward calorimeters had to be redone. This calibration is performed by inter-calibrating the forward electron energy scale using pairs of a central and a forward electron and the previously derived central electron energy calibration. The uncertainty is shown to be

  19. Measurement of the forward-backward asymmetry of Z boson decays in electron-positron pairs with the ATLAS detector in proton-proton collisions at √(s)=7 TeV at the LHC

    International Nuclear Information System (INIS)

    In this thesis the measurement of the effective weak mixing angle sin2θWeff in proton-proton collisions is described. The results are extracted from the forward-backward asymmetry (AFB) in electron-positron final states at the ATLAS experiment at the LHC. The AFB is defined upon the distribution of the polar angle between the incoming quark and outgoing lepton. The signal process used in this study is the reaction pp→ Z/γ*+X→e+e-+X taking a total integrated luminosity of 4.8 fb-1 of data into account. The data was recorded at a proton-proton center-of-mass energy of √(s)=7 TeV. The weak mixing angle is a central parameter of the electroweak theory of the Standard Model (SM) and relates the neutral current interactions of electromagnetism and weak force. The higher order corrections on sin2θWeff are related to other SM parameters like the mass of the Higgs boson. Because of the symmetric initial state constellation of colliding protons, there is no favoured forward or backward direction in the experimental setup. The reference axis used in the definition of the polar angle is therefore chosen with respect to the longitudinal boost of the electron-positron final state. This leads to events with low absolute rapidity have a higher chance of being assigned to the opposite direction of the reference axis. This effect called dilution is reduced when events at higher rapidities are used. It can be studied including electrons and positrons in the forward regions of the ATLAS calorimeters. Electrons and positrons are further referred to as electrons. To include the electrons from the forward region, the energy calibration for the forward calorimeters had to be redone. This calibration is performed by inter-calibrating the forward electron energy scale using pairs of a central and a forward electron and the previously derived central electron energy calibration. The uncertainty is shown to be dominated by the systematic variations. The extraction of sin2θWeff is

  20. Development Zones Flourish in Beijing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Based on the Beijing Municipal Government's plans for developing the city and neighboring suburbs,and after more than 10 years in development,the Beijing Development Zones have taken shape,each with their own characteristics.

  1. A calibration system for Compton polarimetry at e+e- linear colliders

    Science.gov (United States)

    Vormwald, B.; List, J.; Vauth, A.

    2016-01-01

    Polarimetry with permille-level precision is essential for future electron-positron linear colliders. Compton polarimeters can reach negligible statistical uncertainties within seconds of measurement time. The dominating systematic uncertainties originate from the response and alignment of the detector which records the Compton scattered electrons. The robust baseline technology for the Compton polarimeters foreseen at future linear colliders is based on an array of gas Cherenkov detectors read out by photomultipliers. In this paper, we will present a calibration method which promises to monitor nonlinearities in the response of such a detector at the level of a few permille. This method has been implemented in an LED-based calibration system which matches the existing prototype detector. The performance of this calibration system is sufficient to control the corresponding contribution to the total uncertainty on the extracted polarisation to better than 0.1%.

  2. A Calibration System for Compton Polarimetry at $e^+e^-$ Linear Colliders

    CERN Document Server

    Vormwald, Benedikt; Vauth, Annika

    2015-01-01

    Polarimetry with permille-level precision is essential for future electron-positron linear colliders. Compton polarimeters can reach negligible statistical uncertainties within seconds of measurement time. The dominating systematic uncertainties originate from the response and alignment of the detector which records the Compton scattered electrons. The robust baseline technology for the Compton polarimeters foreseen at future linear colliders is based on an array of gas Cherenkov detectors read out by photomultipliers. In this paper, we will present a calibration method which promises to monitor nonlinearities in the response of such a detector at the level of a few permille. This method has been implemented in an LED-based calibration system which matches the existing prototype detector. The performance of this calibration system is sufficient to control the corresponding contribution to the total uncertainty on the extracted polarisation to better than $0.1\\%$.

  3. A calibration system for Compton polarimetry at e+e- linear colliders

    International Nuclear Information System (INIS)

    Polarimetry with permille-level precision is essential for future electron-positron linear colliders. Compton polarimeters can reach negligible statistical uncertainties within seconds of measurement time. The dominating systematic uncertainties originate from the response and alignment of the detector which records the Compton scattered electrons. The robust baseline technology for the Compton polarimeters foreseen at future linear colliders is based on an array of gas Cherenkov detectors read out by photomultipliers. In this paper, we will present a calibration method which promises to monitor nonlinearities in the response of such a detector at the level of a few permille. This method has been implemented in an LED-based calibration system which matches the existing prototype detector. The performance of this calibration system is sufficient to control the corresponding contribution to the total uncertainty on the extracted polarisation to better than 0.1%.

  4. Mitigation of ground motion effects via feedback systems in the Compact Linear Collider

    CERN Document Server

    Pfingstner, Jürgen; Schmickler, Hermann; Schulte, Daniel

    The Compact Linear Collider (CLIC) is a future multi-TeV electron positron collider, which is currently being designed at CERN. To achieve its ambitious goals, CLIC has to produce particle beams of the highest quality, which makes the accelerator very sensitive to ground motion. Four mitigation methods have been foreseen by the CLIC design group to cope with the feasibility issue of ground motion. This thesis is concerned with the design of one of these mitigation methods, named linac feedback (L-FB), but also with the simultaneous simulation and validation of all mitigation methods. Additionally, a technique to improve the quality of the indispensable system knowledge has been developed. The L-FB suppresses beam oscillations along the accelerator. Its design is based on the decoupling of the overall accelerator system into independent channels. For each channel an individual compensator is found with the help of a semi- automatic control synthesis procedure. This technique allows the designer to incorporate ...

  5. Radiative Neutrino Mass Model at the $e^{-}e^{+}$ Linear Collider

    CERN Document Server

    Ahriche, Amine; Soualah, Rachik

    2014-01-01

    We study the phenomenology of a Standard Model (SM) extension with two charged singlet scalars and three right handed (RH) neutrinos at an electron-positron collider. In this model, the neutrino mass is generated radiatively at three-loop, the lightest RH neutrino is a good dark matter candidate; and the electroweak phase transition strongly first order as required for baryogenesis. We focus on the process $e^{+}+e^{-}\\rightarrow e^{-}\\mu^{+}+E_{miss}$, where the model contains new lepton flavor violating interactions that contribute to the missing energy. We investigate the feasibility of detecting this process at future $e^{-}e^{+}$ linear colliders at different center of mass energies: $E_{CM}$=250, 350, 500 GeV and 1 TeV.

  6. Top quark pair production and calorimeter energy resolution studies at a future collider experiment

    CERN Document Server

    Seidel, Katja

    This thesis is focused on detector concepts and analyses investigated at a future linear electron positron collider. For precision measurements at such a collider, the CALICE collaboration develops imaging calorimeters, which are characterized by a fine granularity. CALICE has constructed prototypes of several design options for electromagnetic and hadronic calorimeters and has successfully operated these detectors during combined test beam programs at DESY, CERN and Fermilab. To improve the hadronic energy reconstruction and energy resolution of a hadron calorimeter prototype with analog readout three software compensation techniques are presented in this thesis, of which one is a local and two are global software compensation approaches. One method is based on a neural network to optimize the energy reconstruction, while two are energy weighting techniques, depending on the energy density. Weight factors are extracted from and applied to simulated and test beam data and result in an average energy resolutio...

  7. Production of polarized τ pairs and tests of CP violation using polarized e± colliders near threshold

    International Nuclear Information System (INIS)

    We consider the production of τ pairs by electron-positron colliding beams at the maximum cross section near the threshold. At this energy τ pairs are produced mostly in the s-wave which implies that the spin of the τ pairs are almost always pointing in the beam direction independent of the production angle. When both electrons and positrons are longitudinally polarized in the same direction, for example 90%, one can obtain τ pairs with 99% polarization in the direction of the polarization vectors of the incident beams. Tests of CP violation and study of the structure of weak interactions using such polarized τ pairs are discussed

  8. Physics Accomplishments and Future Prospects of the BES Experiments at the BEPC Collider

    CERN Document Server

    Briere, Roy A; Mitchell, Ryan E

    2016-01-01

    The cornerstone of the Chinese experimental particle physics program consists of a series of experiments performed in the tau-charm energy region. China began building e+e- colliders at the Institute for High Energy Physics in Beijing more than three decades ago. Beijing Electron Spectrometer, BES, is the common root name for the particle physics detectors operated at these machines. The development of the BES program is summarized and highlights of the physics results across several topical areas are presented.

  9. Catch Hilton Beijing

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Ready to spice up Beijing's nightlife? Come on to Zeta Bars, Hilton! If sneak previews are anything to go by, it's clear that The Third Ring will consistently perform to sellout crowds keen to catch a glimpse of the stunningly redesigned restaurants and bars that line the tri-level

  10. Beijing Time Travel

    Institute of Scientific and Technical Information of China (English)

    ROBERT; T.TUOHEY

    2010-01-01

    Daily travel within Beijing need not be anymore troublesome than going about any major metropolis.Simply,certain basic facts need to be kept in mind,and ordinary precautions taken.Essentially,it’s the same situation as midtown Manhattan or downtown Tokyo,except everyone’s speaking Chinese.

  11. Beijing Time Travel

    Institute of Scientific and Technical Information of China (English)

    ROBERT T.TUOHEY

    2010-01-01

    @@ Dally travel within Beijing need not be anymore troublesome than going about any major metropolis.Simply,certain basic facts need to be kept in mind,and ordinary precautions taken.Essentially,it's the same situation as midtown Manhattan or downtown Tokyo,except everyone's speaking Chinese.

  12. Exploring the New Beijing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Eating Ghost Street This street is home to more than 150 storefronts,over 100 of which offer a variety of different foods.In all of Beijing this may be the only street that has such a large number of restaurants.

  13. Beijing in Pictures

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    With a history of more than 3,000 years, Beijing is famousfor its architectural styles, and is regarded as the city with themost diversified construction in China. Its ancient charm can beseen in its unique imperial palaces, courtyards and hutongs. The

  14. Beijing Development Zones

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Beijing Badaling Development Area The Development Area is planned to cover an area of 6.56 km2.Currently,more than 300 enterprises have located in the area.Their investments add up to about RMB 1 billion.Major business trades include machine building,mineral ore processing,medicine,electronic parts,foodstuff processing,and warehousing transportation.

  15. Life in Beijing Prison

    Institute of Scientific and Technical Information of China (English)

    LIU XIAOLIN; ZHAO JINGJING

    2007-01-01

    @@ The Beijing Prison, located in the suburbs about one hour's drive from downtown, has opened to the public. People over 18 years old can now apply for a one-day visit to get a peep into the inmates' living cells, parlors and psychological counseling centers of the nearly 1,600 male convicts sentenced to more than 15 years behind bars.

  16. Top quark pair production and calorimeter energy resolution studies at a future collider experiment

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, Katja

    2012-03-27

    This thesis is focused on detector concepts and analyses investigated at a future linear electron positron collider. For precision measurements at such a collider, the CALICE collaboration develops imaging calorimeters, which are characterized by a fine granularity. CALICE has constructed prototypes of several design options for electromagnetic and hadronic calorimeters and has successfully operated these detectors during combined test beam programs at DESY, CERN and Fermilab. To improve the hadronic energy reconstruction and energy resolution of a hadron calorimeter prototype with analog readout three software compensation techniques are presented in this thesis, of which one is a local and two are global software compensation approaches. One method is based on a neural network to optimize the energy reconstruction, while two are energy weighting techniques, depending on the energy density. Weight factors are extracted from and applied to simulated and test beam data and result in an average energy resolution improvement of 15 - 25% compared to a reconstruction without software compensation. Whether such software compensation techniques are also applicable to a detector concept for a future linear electron positron collider is studied in the second part of this thesis. Simulated data, two different hadronic detector models and a local software compensation technique are used for this study. The energy resolutions for single hadrons and for jets are presented with and without software compensation. In the third part of this thesis, a study on top quark pair production at a center-of-mass energy of 500 GeV at the proposed electron positron collider CLIC is presented. The analysis is based on full detector simulations, including realistic background contributions dominated by two photon processes. The mass and width of the top quark are studied in fully-hadronic and semi-leptonic decays of top quark pairs using event samples of signal and Standard Model background

  17. Whither colliders after the Large Hadron Collider?

    Indian Academy of Sciences (India)

    Rolf-Dieter Heuer

    2012-11-01

    This paper presents options for high-energy colliders at the energy frontier for the years to come. The immediate plans include the exploitation of the LHC at its design luminosity and energy as well as upgrades to the LHC (luminosity and energy) and to its injectors. This may be complemented by a linear electron–positron collider, based on the technology being developed by the Compact Linear Collider and by the International Linear Collider, by a high-energy electron– proton machine, the LHeC, and/or by a muon collider. This contribution describes the various future directions, all of which have a unique value to add to experimental particle physics, and concludes by outlining the key messages for the way forward.

  18. Planar dust-acoustic waves in electron-positron-ion-dust plasmas with dust-size distribution under higher-order transverse perturbations

    International Nuclear Information System (INIS)

    Propagation of small but finite nonlinear dust-acoustic solitary waves are investigated in a planar unmagnetized dusty plasma, which consists of electrons, positrons, ions and negatively charged dust particles with different sizes and masses. A Kadomtsev-Petviashvili (KP) equation is obtained by using reductive perturbation method. The effect of positron density and positron- electron temperature ratio on dust-acoustic solitary structures are studied. Numerical results show that the increase in positron number density increases the amplitude of hump-like solitons but decreases the dip-like solitary waves. Furthermore, increase in the positron-electron temperature ratio results in the decrease of the amplitude of dip-like solitary waves. It seems that both the dip and hump-like solitary waves can exist in this system. Our results also suggest that the dust-size distribution has a significant role on the amplitude of the solitary waves. (author)

  19. Search for new physics in high-mass electron-positron events in pp[over] collisions at square root s = 1.96 TeV.

    Science.gov (United States)

    Aaltonen, T; Abulencia, A; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carrillo, S; Carlsmith, D; Carosi, R; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Cilijak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; DaRonco, S; Datta, M; D'Auria, S; Davies, T; Dagenhart, D; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'Orso, M; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Dörr, C; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraan, A C; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; Lecompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; Macqueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moon, C S; Moore, R; Morello, M; Fernandez, P Movilla; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S

    2007-10-26

    We report the results of a search for a narrow resonance in electron-positron events in the invariant mass range of 150-950 GeV/c(2) using 1.3 fb(-1) of pp[over] collision data at square root s = 1.96 TeV collected by the CDF II detector at Fermilab. No significant evidence of such a resonance is observed and we interpret the results to exclude the standard-model-like Z' with a mass below 923 GeV/c(2) and the Randall-Sundrum graviton with a mass below 807 GeV/c(2) for k/M[over](pl) = 0.1, both at the 95% confidence level. Combining with diphoton data excludes the Randall-Sundrum graviton for masses below 889 GeV/c(2) for k/M[over](pl) = 0.1. PMID:17995318

  20. Three-dimensional electron-positron momentum distribution of O{sup 3+}-irradiated 6H SiC using two positron spectroscopy techniques simultaneously

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Christopher; Burggraf, Larry; Petrosky, James [Air Force Institute of Technology, AFIT/ENP, 2950 Hobson Way, Wright-Patterson Air Force Base, OH 45433 (United States); Adamson, Paul, E-mail: christopher.williams@afit.edu [Stockpile Research, Development and Engineering Division, Office of Defense Programs, National Nuclear Security Administration, 1000 Independence Ave SW, Washington, DC 20585 (United States)

    2011-01-01

    A three-dimensional (3D) positron annihilation spectroscopy system (3DPASS) capable of determining 3D electron-positron (e{sup -}-e{sup +}) momentum densities from measurements of deviations from co-linearity and energies of photons from e{sup -}-e{sup +} annihilation events was employed to examine the effects of O-atom defects in 6H SiC. Three-dimensional momentum datasets were determined for 6H SiC irradiated with 24 MeV O{sup 3+} ions. Angular correlation of annihilation radiation (ACAR) and coincidence Doppler-broadening of annihilation radiation (CDBAR) analyses are presented. In addition, a novel technique is illustrated for analyzing 3D momentum datasets in which the parallel momentum component, p{sub ||} (obtained from the CDBAR measurement) is selected for annihilation events that possess a particular perpendicular momentum component, p{sub -} observed in the 2D ACAR spectrum.

  1. Stability analysis solutions for nonlinear three-dimensional modified Korteweg-de Vries-Zakharov-Kuznetsov equation in a magnetized electron-positron plasma

    Science.gov (United States)

    Seadawy, Aly R.

    2016-08-01

    The nonlinear three-dimensional modified Korteweg-de Vries-Zakharov-Kuznetsov ​(mKdV-ZK) equation governs the behavior of weakly nonlinear ion-acoustic waves in magnetized electron-positron plasma which consists of equal hot and cool components of each species. By using the reductive perturbation procedure leads to a mKdV-ZK equation governing the oblique propagation of nonlinear electrostatic modes. The stability of solitary traveling wave solutions of the mKdV-ZK equation to three-dimensional long-wavelength perturbations is investigated. We found the electrostatic field potential and electric field in form traveling wave solutions for three-dimensional mKdV-ZK equation. The solutions for the mKdV-ZK equation are obtained precisely and efficiency of the method can be demonstrated.

  2. Particle-in-cell simulation for parametric decays of a circularly polarized Alfvén wave in relativistic thermal electron-positron plasma

    Energy Technology Data Exchange (ETDEWEB)

    López, Rodrigo A., E-mail: rlopez186@gmail.com; Muñoz, Víctor [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Viñas, Adolfo F. [NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Mail Code 673, Greenbelt, Maryland 20771 (United States); Alejandro Valdivia, J. [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Santiago (Chile)

    2014-03-15

    Parametric decays of a left-handed circularly polarized Alfvén wave propagating along a constant background magnetic field in a relativistic thermal electron-positron plasma are studied by means of a one dimensional relativistic particle-in-cell simulation. Relativistic effects are included in the Lorentz equation for the momentum of the particles and in their thermal motion, by considering a Maxwell-Jüttner velocity distribution function for the initial condition. In the linear stage of the simulation, we find many instabilities that match the predictions of relativistic fluid theory. In general, the growth rates of the instabilities increase as the pump wave amplitude is increased, and decrease with a raise in the plasma temperatures. We have confirmed that for very high temperatures the Alfvén branch is suppressed, consistent with analytical calculations.

  3. Propagation and Generation of Electromagnetic Waves at Proton Gyrofrequencies in a Relativistic Electron-Positron Plasma. II. Excitation of Electromagnetic Waves

    Science.gov (United States)

    Zheleznyakov, V. V.; Bespalov, P. A.

    2016-04-01

    In part I of this work [1], we study the dispersion characteristics of low-frequency waves in a relativistic electron-positron plasma. In part II, we examine the electromagnetic wave instability in this plasma caused by an admixture of nonrelativistic protons with energy comparable with the energy of relativistic low-mass particles. The instability occurs in the frequency band between the fundamental harmonic of proton gyrofrequency and the fundamental harmonic of relativistic electron gyrofrequency. The results can be used for the interpretation of known observations of the pulsar emissions obtained with a high time and frequency resolution. The considered instability can probably be the initial stage of the microwave radio emission nanoshots typical of the pulsar in the Crab Nebula.

  4. Measurement of the Z boson differential cross-section in transverse momentum in the electron-positron channel with the ATLAS detector at LHC

    CERN Document Server

    Martinez, Homero

    This work presents the measurement of the Z boson differential cross section in transverse momentum (ptz), in the electron-positron decay channel, using the ATLAS detector at the LHC. The measurement is done using 4.64 fb−1 of proton-proton collision data, collected in 2011 at a center-of-mass energy of 7 TeV. The result is combined with an independent measurement done in the muon-antimuon decay channel. The measurement is done up to ptz = 800 GeV, and has a typical uncertainty of 0.5 % for ptz < 60 GeV, rising up to 5 % towards the end of the spectrum. The measurement is compared to theoretical models and Monte Carlo generators predictions.

  5. Optimizing electron-positron pair production on kilojoule-class high-intensity lasers for the purpose of pair-plasma creation

    Science.gov (United States)

    Myatt, J.; Delettrez, J. A.; Maximov, A. V.; Meyerhofer, D. D.; Short, R. W.; Stoeckl, C.; Storm, M.

    2009-06-01

    Expressions for the yield of electron-positron pairs, their energy spectra, and production rates have been obtained in the interaction of multi-kJ pulses of high-intensity laser light interacting with solid targets. The Bethe-Heitler conversion of hard x-ray bremsstrahlung [D. A. Gryaznykh, Y. Z. Kandiev, and V. A. Lykov, JETP Lett. 67, 257 (1998); K. Nakashima and H. Takabe, Phys. Plasmas 9, 1505 (2002)] is shown to dominate over direct production (trident process) [E. P. Liang, S. C. Wilks, and M. Tabak, Phys. Rev. Lett. 81, 4887 (1998)]. The yields and production rates have been optimized as a function of incident laser intensity by the choice of target material and dimensions, indicating that up to 5×1011 pairs can be produced on the OMEGA EP laser system [L. J. Waxer , Opt. Photonics News 16, 30 (2005)]. The corresponding production rates are high enough to make possible the creation of a pair plasma.

  6. Search for New Physics in High Mass Electron-Positron Events in ppbar Collisions at $\\sqrt{s}$ = 1.96 TeV

    CERN Document Server

    Aaltonen, T; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P H; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bölla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, Yu; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carrillo, S; Carlsmith, D; Carosi, R; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Cilijak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca-Almenar, C; Cuevas-Maestro, J; Culbertson, R; Cully, J C; Da Ronco, S; Datta, M; D'Auria, S; Davies, T; Dagenhart, D; De Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'Orso, Mauro; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Dorr, C; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernández, J P; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; García, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Gómez, G; Gómez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Group, R C; Grundler, U; Guimarães da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Höcker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraan, A C; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lu, R S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Mäki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martinez-Ballarin, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtälä, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moon, C S; Moore, R; Morello, M; Movilla-Fernández, P A; Mülmenstädt, J; Mukherjee, A; Müller, T; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Österberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, Aldo L; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P B; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Salto, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shalhout, S Z; Shapiro, M D; Shears, T G; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakian, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Söderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; Saint-Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuno, S; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; Van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Veramendi, G; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Vollrath, I; Volobuev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S

    2007-01-01

    We report the results of a search for a narrow resonance in electron-positron events in the invariant mass range of 150-950 GeV/c^2 using 1.3 fb^-1 of ppbar collision data at $\\sqrt{s}$ = 1.96 TeV collected by the CDF II detector at Fermilab. No significant evidence of such a resonance is observed and we interpret the results to exclude the standard model-like Z' with a mass below 923 GeV/c^2 and the Randall-Sundrum graviton with a mass below 807 GeV/c^2 for k/M_pl=0.1, both at the 95% confidence level. Combining with di-photon data excludes the Randall-Sundrum graviton for masses below 889 GeV/c^2 for k/M_pl=0.1.

  7. Beijing International Fashion Brand Promotion Week Opened

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Under the support of China National Garment Association,Beijing Municipal Bureau of Industrial Development, France Advanced Fashion Institute, Fashion Beijing Expo Organizing Committee and Beijing Fashion Textile Industry Association organized 2006 Autumn & Winter Beijing International Fashion Brand Promotion Week in Beijing Asia Hotel from September 20 to 23.

  8. Proceedings of the 2005 International Linear Collider Workshop (LCWS05)

    Energy Technology Data Exchange (ETDEWEB)

    Hewett, JoAnne, (ed.); /SLAC

    2006-12-18

    Exploration of physics at the TeV scale holds the promise of addressing some of our most basic questions about the nature of matter, space, time, and energy. Discoveries of the Electroweak Symmetry Breaking mechanism, Supersymmetry, Extra Dimensions of space, Dark Matter particles, and new forces of nature are all possible. We have been waiting and planning for this exploration for over 20 years. In 2007 the Large Hadron Collider at CERN will begin its operation and will break into this new energy frontier. A new era of understanding will emerge as the LHC data maps out the Terascale. With the LHC discoveries, new compelling questions will arise. Responding to these questions will call for a new tool with greater sensitivity--the International Linear Collider. Historically, the most striking progress in the exploration of new energy frontiers has been made from combining results from hadron and electron-positron colliders. The precision measurements possible at the ILC will reveal the underlying theory which gave rise to the particles discovered at the LHC and will open the window to even higher energies. The world High Energy Physics community has reached an accord that an e+e- linear collider operating at 0.5-1.0 TeV would provide both unique and essential scientific opportunities; the community has endorsed with highest priority the construction of such a machine. A major milestone toward this goal was reached in August 2004 when the International Committee on Future Accelerators approved a recommendation for the technology of the future International Linear Collider. A global research and design effort is now underway to construct a global design report for the ILC. This endeavor is directed by Barry Barrish of the California Institute of Technology. The offer, made by Jonathan Dorfan on the behalf of ICFA, and acceptance of this directorship took place during the opening plenary session of this workshop. The 2005 International Linear Collider Workshop was held

  9. P P collider physics

    Energy Technology Data Exchange (ETDEWEB)

    Demarteau, M. (State Univ. of New York, Stony Brook, NY (United States))

    1992-04-01

    A brief introduction to {bar p}p collider physics is given. Selected results from the collider experiments at the CERN S{bar p}pS and the Tevatron collider are described. The emphasis is on experimental aspects of {bar p}p collisions. Minimum bias physics and the production of jets, Intermediate Vector Bosons and heavy flavors is reviewed. The outlook for physics at hadron colliders for the near future is briefly discussed.

  10. SuperB: Next-Generation e+e− B-factory Collider

    CERN Document Server

    Novokhatski, A; Chao, A; Nosochkov, Y; Seeman, J T; Sullivan, M K; Wienands, J T; Wittmer, W; Baylac, M A; Bourrion, O; Monseu, N; Vescovi, C; Bettoni, S; Biagini, M E; Boni, R; Boscolo, M; Demma, T; Drago, A; Esposito, M; Guiducci, S; Preger, M A; Raimondi, P; Tomassini, S; Zobov, M; Bogomyagkov, A V; Nikitin, S A; Piminov, P A; Shatilov, D N; Sinyatkin, S V; Vobly, P; Bolzon, B; Brunetti, L; Jeremie, A; A. Chancé; Fabbricatore, P; Farinon, S; Musenich, R; Liuzzo, S M; Paoloni, E; Okunev, I N; Poirier, F; Rimbault, C; Variola, A

    2011-01-01

    The SuperB international team continues to optimize the design of an electron-positron collider, which will allow the enhanced study of the origins of flavor physics. The project combines the best features of a linear collider (high single-collision luminosity) and a storage-ring collider (high repetition rate), bringing together all accelerator physics aspects to make a very high luminosity of 1036 cm-2 s-1. This asymmetric-energy collider with a polarized electron beam will produce hundreds of millions of B-mesons at the Y(4S) resonance. The present design is based on extremely low emittance beams colliding at a large Piwinski angle to allow very low ßy* without the need for ultra short bunches. Use of crab-waist sextupoles will enhance the luminosity, suppressing dangerous resonances and allowing for a higher beam-beam parameter. The project has flexible beam parameters, improved dynamic aperture, and spin-rotators in the Low Energy Ring for longitudinal polarization of the electron beam at the Interactio...

  11. Berkeley mini-collider

    International Nuclear Information System (INIS)

    The Berkeley Mini-Collider, a heavy-ion collider being planned to provide uranium-uranium collisions at T/sub cm/ less than or equal to 4 GeV/nucleon, is described. The central physics to be studied at these energies and our early ideas for a collider detector are presented

  12. Development work for a superconducting linear collider

    Science.gov (United States)

    Matheisen, Axel

    1995-01-01

    For future linear e(+)e(-) colliders in the TeV range several alternatives are under discussion. The TESLA approach is based on the advantages of superconductivity. High Q values of the accelerator structures give high efficiency for converting RF power into beam power. A low resonance frequency for the RF structures can be chosen to obtain a large number of electrons (positrons) per bunch. For a given luminosity the beam dimensions can be chosen conservatively which leads to relaxed beam emittance and tolerances at the final focus. Each individual superconducting accelerator component (resonator cavity) of this linear collider has to deliver an energy gain of 25 MeV/m to the beam. Today s.c. resonators are in use at CEBAF/USA, at DESY/Germany, Darmstadt/Germany KEK/Japan and CERN/Geneva. They show acceleration gradients between 5 MV/m and 10 MV/m. Encouraging experiments at CEA Saclay and Cornell University showed acceleration gradients of 20 MV/m and 25 MV/m in single and multicell structures. In an activity centered at DESY in Hamburg/Germany the TESLA collaboration is constructing a 500 MeV superconducting accelerator test facility (TTF) to demonstrate that a linear collider based on this technique can be built in a cost effective manner and that the necessary acceleration gradients of more than 15 MeV/m can be reached reproducibly. The test facility built at DESY covers an area of 3.000 m2 and is divided into 3 major activity areas: (1) The testlinac, where the performance ofthe modular components with an electron beam passing the 40 m long acceleration section can be demonstrated. (2) The test area, where all individual resonators are tested before installation into a module. (3) The preparation and assembly area, where assembly of cavities and modules take place. We report here on the design work to reach a reduction of costs compared to actual existing superconducting accelerator structures and on the facility set up to reach high acceleration gradients in

  13. Application of conventional laser technology to gamma-gamma colliders

    International Nuclear Information System (INIS)

    A future e-e+ (electron-positron) linear collider can be configured with perhaps minimal modification to serve as an γ-γ (gamma-gamma) or a e--γ collider. This is accomplished by Compton-backscattering low energy photons (from a laser source) off of the high-energy electron beams prior to the crossing of the electron beams. However, to be competitive with the e-e+ configuration, the luminosity cannot be compromised in the process. This requires that the laser source deliver a sufficient number of photons per pulse with a pulse format and rate matching that of the electron beams. As it turns out, this requires an average optical power of 5 to 15 kW from the laser which is beyond the current state of the art. In this paper, the authors address how to generate the required pulse format and how the high average power requirement can be met with conventional laser technology. They also address concerns about the survivability of mirrors located near the interaction point. Finally, they list a program of research and development which addresses some of the unknowns in such a system

  14. The International Linear Collider Technical Design Report - Volume 4: Detectors

    CERN Document Server

    ed.; Burrows, Philip N.; Fuster, Juan; Peskin, Michael; Stanitzki, Marcel; Sugimoto, Yasuhiro; Yamada, Sakue; Yamamoto, Hitoshi

    2013-01-01

    The International Linear Collider Technical Design Report (TDR) describes in four volumes the physics case and the design of a 500 GeV centre-of-mass energy linear electron-positron collider based on superconducting radio-frequency technology using Niobium cavities as the accelerating structures. The accelerator can be extended to 1 TeV and also run as a Higgs factory at around 250 GeV and on the Z0 pole. A comprehensive value estimate of the accelerator is give, together with associated uncertainties. It is shown that no significant technical issues remain to be solved. Once a site is selected and the necessary site-dependent engineering is carried out, construction can begin immediately. The TDR also gives baseline documentation for two high-performance detectors that can share the ILC luminosity by being moved into and out of the beam line in a "push-pull" configuration. These detectors, ILD and SiD, are described in detail. They form the basis for a world-class experimental programme that promises to incr...

  15. The International Linear Collider - Volume 1: Executive Summary

    CERN Document Server

    Brau, James E.; Foster, Brian; Fuster, Juan; Harrison, Mike; Paterson, James McEwan; Peskin, Michael; Stanitzki, Marcel; Walker, Nicholas; Yamamoto, Hitoshi

    2013-01-01

    The International Linear Collider Technical Design Report (TDR) describes in four volumes the physics case and the design of a 500 GeV centre-of-mass energy linear electron-positron collider based on superconducting radio-frequency technology using Niobium cavities as the accelerating structures. The accelerator can be extended to 1 TeV and also run as a Higgs factory at around 250 GeV and on the Z0 pole. A comprehensive value estimate of the accelerator is give, together with associated uncertainties. It is shown that no significant technical issues remain to be solved. Once a site is selected and the necessary site-dependent engineering is carried out, construction can begin immediately. The TDR also gives baseline documentation for two high-performance detectors that can share the ILC luminosity by being moved into and out of the beam line in a "push-pull" configuration. These detectors, ILD and SiD, are described in detail. They form the basis for a world-class experimental programme that promises to incr...

  16. Ingot Nb based SRF technology for the International Linear Collider

    International Nuclear Information System (INIS)

    The International Linear Collider (ILC) is anticipated to be built as the next energy-frontier electron-positron colliding accelerator with a global effort in particle physics. Niobium based Superconducting Radio-Frequency (SRF) technology is required to provide beam-accelerating structure with elliptical cavity strings to linearly accelerate the electron and positron beams up to 250 GeV and to realize a center-of-mass energy of 500 GeV in collisions. The accelerator design and R&D efforts progressed, and the ILC Technical Design Report (ILC-TDR) was published in 2013. Niobium will take a critical role to generate electric field gradient with a frequency of 1.3 GHz, for accelerating the beam with the best efficiency, in energy balance, using RF superconductivity. This paper discusses a technical approach to provide Nb material (ingot) and thin disks for producing the elliptical cavity structure, with direct slicing from Nb ingot having sufficiently optimized purity and residual resistance ration (RRR) necessary for the ILC SRF cavities

  17. Ingot Nb based SRF technology for the International Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Akira, E-mail: akira.yamamoto@kek.jp [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801 (Japan); European Organization for Nuclear Research (CERN) 23 Genève, CH-1211 (Switzerland); Yamanaka, Masashi, E-mail: masashi.yamanaka@kek.jp [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801 (Japan); Myneni, Ganapati, E-mail: ganapati@isohim.org [Jefferson Lab (JLab) Newport News, VA, 23606 (United States)

    2015-12-04

    The International Linear Collider (ILC) is anticipated to be built as the next energy-frontier electron-positron colliding accelerator with a global effort in particle physics. Niobium based Superconducting Radio-Frequency (SRF) technology is required to provide beam-accelerating structure with elliptical cavity strings to linearly accelerate the electron and positron beams up to 250 GeV and to realize a center-of-mass energy of 500 GeV in collisions. The accelerator design and R&D efforts progressed, and the ILC Technical Design Report (ILC-TDR) was published in 2013. Niobium will take a critical role to generate electric field gradient with a frequency of 1.3 GHz, for accelerating the beam with the best efficiency, in energy balance, using RF superconductivity. This paper discusses a technical approach to provide Nb material (ingot) and thin disks for producing the elliptical cavity structure, with direct slicing from Nb ingot having sufficiently optimized purity and residual resistance ration (RRR) necessary for the ILC SRF cavities.

  18. Ingot Nb based SRF technology for the International Linear Collider

    Science.gov (United States)

    Yamamoto, Akira; Yamanaka, Masashi; Myneni, Ganapati

    2015-12-01

    The International Linear Collider (ILC) is anticipated to be built as the next energy-frontier electron-positron colliding accelerator with a global effort in particle physics. Niobium based Superconducting Radio-Frequency (SRF) technology is required to provide beam-accelerating structure with elliptical cavity strings to linearly accelerate the electron and positron beams up to 250 GeV and to realize a center-of-mass energy of 500 GeV in collisions. The accelerator design and R&D efforts progressed, and the ILC Technical Design Report (ILC-TDR) was published in 2013. Niobium will take a critical role to generate electric field gradient with a frequency of 1.3 GHz, for accelerating the beam with the best efficiency, in energy balance, using RF superconductivity. This paper discusses a technical approach to provide Nb material (ingot) and thin disks for producing the elliptical cavity structure, with direct slicing from Nb ingot having sufficiently optimized purity and residual resistance ration (RRR) necessary for the ILC SRF cavities.

  19. Photon collider Higgs factories

    CERN Document Server

    Telnov, V I

    2014-01-01

    The discovery of the Higgs boson (and still nothing else) have triggered appearance of many proposals of Higgs factories for precision measurement of the Higgs properties. Among them there are several projects of photon colliders (PC) without e+e- in addition to PLC based on e+e- linear colliders ILC and CLIC. In this paper, following a brief discussion of Higgs factories physics program I give an overview of photon colliders based on linear colliders ILC and CLIC, and of the recently proposed photon-collider Higgs factories with no e+e- collision option based on recirculation linacs in ring tunnels.

  20. Giovanni Arrighi in Beijing

    OpenAIRE

    Ganesh Trichur; Steven Sherman

    2015-01-01

    Giovanni Arrighi's Adam Smith in Beijing (ASB) subverts the temporality and conceptual vocabulary employed by most writers working in a Marxist tradition. In this view, capitalism is a mode of production which eventually encompasses the entire world. Perhaps it began in England and expanded from there. Perhaps its expansion through colonial empires should be seen as part of its constitution, rather than an after effect (i.e. the perspective of Wallerstein). In any case, it eventually dominate...

  1. Beijing Tsinghua Solar Ltd.

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Beijing Tsinghua Solar Ltd. is backed by Tsinghua University, one of the most prestigious universities in China. Tsinghua Solar invented "graded Al-N/Al selective coating," which is the key technology of all-glass evacuated solar collector tubes. The company owns the independent intellectual property rights over the key technology of all-glass vacuum solar water heaters. The registered capital of the company is 153.5 mil-

  2. Hadron Colliders and Hadron Collider Physics Symposium

    Directory of Open Access Journals (Sweden)

    Denisov D.

    2013-05-01

    Full Text Available This article summarizes main developments of the hadron colliders and physics results obtained since their inception around forty years ago. The increase in the collision energy of over two orders of magnitude and even larger increases in luminosity provided experiments with unique data samples. Developments of full acceptance detectors, particle identification and analysis methods provided fundamental discoveries and ultra-precise measurements which culminated in the completion and in depth verification of the Standard Model. Hadron Collider Physics symposium provided opportunities for those working at hadron colliders to share results of their research since 1979 and helped greatly to develop the field of particle physics.

  3. Hadron Colliders and Hadron Collider Physics Symposium

    CERN Document Server

    Denisov, Dmitri

    2013-01-01

    This article summarizes main developments of the hadron colliders and physics results obtained since their inception around forty years ago. The increase in the collision energy of over two orders of magnitude and even larger increases in luminosity provided experiments with unique data samples. Developments of full acceptance detectors, particle identification and analysis methods provided fundamental discoveries and ultra-precise measurements which culminated in the completion and in depth verification of the Standard Model. Hadron Collider Physics symposium provided opportunities for those working at hadron colliders to share results of their research since 1979 and helped greatly to develop the field of particle physics.

  4. Neutral kaon and lambda production in electron-positron annihilation at 29 GeV and the Z boson resonance

    International Nuclear Information System (INIS)

    The production of K0 and Λ in the hadronization of q bar q events from e+e- collisions at 29 GeV and the Z0 resonance is studied using the Mark II detector as upgraded for running at the Stanford Linear Collider. Hadronization processes cannot presently be calculated with Quantum Chromodynamics; instead, hadronization models must be used in comparisons with data. In these models, hadronization occurs at local energy scales of a few GeV, a level at which small differences in quark and diquark mass significantly affect the production of particles such as K0 and Λ, the lightest neutral meson and baryon containing strange quarks. Their production and behavior in hadronic events is a test for the accuracy of our understanding of hadronization. Two-charged- particle decays of the K0 and Λ are isolated within the hadronic event sample. The resulting distribution of K0 and Λ are corrected for inefficiencies and generalized to include all K0 and Λ. Various kinematic distributions of the strange particles are examined. These distributions include the momentum and scaled momentum of the particles. The kinematics of the particles with respect to the original quark direction are examined through the distributions of rapidity and momentum transverse to the thrust both in and out of the event plane. The dependence of K0 and Λ production on the sphericity of the hadronic events is also examined. All these distributions show that the behavior of K0 and Λ in hadronic events is consistent with the hadronization models

  5. $2\\times250$ GeV CLIC $\\gamma\\gamma$ Collider Based on its Drive Beam FEL

    CERN Document Server

    Aksakal, Husnu

    2007-01-01

    CLIC is a linear $e^+e^-$ ($\\gamma\\gamma$) collider project which uses a drive beam to accelerate the main beam. The drive beam provides RF power for each corresponding unit of the main linac through energy extracting RF structures. CLIC has a wide range of center-of-mass energy options from 150 GeV to 3 TeV. The present paper contains optimization of Free Electron Laser (FEL) using one bunch of CLIC drive beam in order to provide polarized light amplification using appropriate wiggler and luminosity spectrum of $\\gamma\\gamma$ collider for $E_{cm}$=0.5 TeV. Then amplified laser can be converted to a polarized high-energy $\\gamma$ beam at the Conversion point (CP-prior to electron positron interaction point) in the process of Compton backscattering. At the CP a powerful laser pulse (FEL) focused to main linac electrons (positrons). Here this scheme described and it is show that CLIC drive beam parameters satisfy the requirement of FEL additionally essential undulator parameters has been defined. Achievable $\\g...

  6. Discovery potential of Higgs boson pair production through 4$\\ell$+$E\\!\\!/$ final states at a 100 TeV collider

    CERN Document Server

    Zhao, Xiaoran; Li, Zhao; Yan, Qi-Shu

    2016-01-01

    We explore the discovery potential of Higgs pair production at a 100 TeV collider via full leptonic mode. The same mode can be explored at the LHC when Higgs pair production is enhanced by new physics. We examine two types of fully leptonic final states and propose a partial reconstruction method. The reconstruction method can reconstruct some kinematic observables. It is found that the $m_{T2}$ variable determined by this reconstruction method and the reconstructed visible Higgs mass are important and crucial to discriminate the signal and background events. It is also noticed that a new variable, denoted as $\\Delta m$ which is defined as the mass difference of two possible combinations, is very useful as a discriminant. We also investigate the interplay between the direct measurements of $t\\bar{t} h$ couplings and other related couplings and trilinear Higgs coupling at hadron colliders and electron-positron colliders.

  7. Measuring the trilinear neutral Higgs boson couplings in the minimal supersymmetric standard model at e+e‑ colliders in the light of the discovery of a Higgs boson

    Science.gov (United States)

    Khosa, Charanjit K.; Pandita, P. N.

    2016-06-01

    We consider the measurement of the trilinear couplings of the neutral Higgs bosons in the minimal supersymmetric standard model (MSSM) at a high energy e+e‑ linear collider in the light of the discovery of a Higgs boson at the CERN Large Hadron Collider (LHC). We identify the state observed at the LHC with the lightest Higgs boson (h0) of the MSSM, and impose the constraints following from this identification, as well as other experimental constraints on the MSSM parameter space. In order to measure trilinear neutral Higgs couplings, we consider different processes where the heavier Higgs boson (H0) of the MSSM is produced in electron-positron collisions, which subsequently decays into a pair of lighter Higgs boson. We identify the regions of the MSSM parameter space where it may be possible to measure the trilinear couplings of the Higgs boson at a future electron-positron collider. A measurement of the trilinear Higgs couplings is a crucial step in the construction of the Higgs potential, and hence in establishing the phenomena of spontaneous symmetry breaking in gauge theories.

  8. Measuring the trilinear neutral Higgs boson couplings in the minimal supersymmetric standard model at $e^+ e^-$ colliders in the light of the discovery of a Higgs boson

    CERN Document Server

    Khosa, Charanjit K

    2016-01-01

    We consider the measurement of the trilinear couplings of the neutral Higgs bosons in the Minimal Supersymmetric Standard Model~(MSSM) at a high energy $e^+ e^-$ linear collider in the light of the discovery of a Higgs boson at the CERN Large Hadron Collider~(LHC). We identify the state observed at the LHC with the lightest Higgs boson~($h^0$) of the MSSM, and impose the constraints following from this identification, as well as other experimental constraints on the MSSM parameter space. In order to measure trilinear neutral Higgs couplings, we consider different processes where the heavier Higgs boson ($H^0$) of the MSSM is produced in electron-positron collisions, which subsequently decays into a pair of lighter Higgs bosons. We identify the regions of the MSSM parameter space where it may be possible to measure the trilinear couplings of the Higgs boson at a future electron-positron collider. A measurement of the trilinear Higgs couplings is a crucial step in the construction of the Higgs potential, and he...

  9. Methods for evaluating physical processes in strong external fields at e{sup +}e{sup -} colliders. Furry picture and quasi-classical approach

    Energy Technology Data Exchange (ETDEWEB)

    Porto, Stefano [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Hartin, Anthony [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Moortgat-Pick, Gudrid [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2013-04-15

    Future linear colliders designs, ILC and CLIC, are expected to be powerful machines for the discovery of Physics Beyond the Standard Model and subsequent precision studies. However, due to the intense beams (high luminosity, high energy), strong electromagnetic fields occur in the beam-beam interaction region. In the context of precision high energy physics, the presence of such strong fields may yield sensitive corrections to the observed electron-positron processes. The Furry picture of quantum states gives a conceptually simple tool to treat physics processes in an external field. A generalization of the quasi-classical operator method (QOM) as an approximation is considered too.

  10. Kempinski Hotel Beijing Lufthansa Center

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A shining star on the eastern part of Beijing Kempinski Hotel Beijing Lufthansa Center is located at the heart of the city, a fully integrated business complex with serviced apartments, top-class offices and showrooms. The hotel offers unrivaled conference, business and leisure facilities ideal for business travelers and leisure guests alike. Its impressive blend of grand Chinese cul-

  11. Beijing: Next International Financial Hub?

    Institute of Scientific and Technical Information of China (English)

    Li Zhen

    2008-01-01

    @@ Beijing's new financial dream On May 5,the Beijing Municipal Government released a notice regarding its plans to spur the financial industry,vowing to put forth a strong effort to become the national financial decision-making center,financial management center and financial information and services center,and formally announcing its ambitious aspiration to become a financial hub with international influence.

  12. Hadron collider physics

    International Nuclear Information System (INIS)

    Hadron colliders provide an important laboratory for testing the Standard Model of strong and electroweak interactions. Because such colliders have the highest available center-of-mass energy (sq. root s), they probe the shortest accessible length scales and hence provide a unique opportunity both to study the fundamental fields of the Standard Model and to search for deviations from the predictions of the Standard Model. This paper presents recent results in the field of experimental hadron collider physics

  13. Standardization in Beijing Opera

    Institute of Scientific and Technical Information of China (English)

    Liu Zhiyang

    2012-01-01

    Beijing Opera is the treasure of Chinese traditional dramatic arts.More than 200 years of artistic practice is the process that makes it mature and standardized.Although it is not described by standardized academic terminologies,all the performances of 'Chang (Singing)','Nian(Speaking)','Zuo (Acting)' and 'Da (Fighting)' have been following standardization requirement which is called "Chengshi (pattem)" in professional language or "Fan'er" in jargou,literally meaning a standard pattern.The pattern is the an technology format which is refined and summarized in accordance with the beautify principles from natural forms of things in life and then standardized to be the commonly adhered.

  14. Probing the nature of electroweak phase transition from particle colliders to gravitational wave detection

    CERN Document Server

    Huang, Fa Peng; Wang, Dong-Gang; Cai, Yi-Fu; Zhang, Xinmin

    2016-01-01

    In this letter, we explore the nature of the electroweak phase transition with both the particle colliders and the gravitational wave (GW) detection. With the observed Higgs mass, the shape of the Higgs potential is fully determined in the standard model of particle physics, however, it could be physically different. Working with the effective field theory, we will show the Higgs potential with a sextic term of the Higgs field included could give the 125 GeV Higgs mass , but a different Higgs potential. Furthermore, this Higgs scenario can produce a strong first order phase transition for the electroweak baryogenesis, and interestingly predict new physics in the Higgs sector, which can be tested at colliders such as the Large Hadron Collider (LHC) and the planning Circular Electron Positron Collider (CEPC). And we will also point out this strong first order phase transition will lead to a detectable GW signal for the GW interferometers , such as eLISA, DECIGO and BBO. Our study in this letter on the electrowe...

  15. Beam Induced Hydrodynamic Tunneling in the Future Circular Collider Components

    Science.gov (United States)

    Tahir, N. A.; Burkart, F.; Schmidt, R.; Shutov, A.; Wollmann, D.; Piriz, A. R.

    2016-08-01

    A future circular collider (FCC) has been proposed as a post-Large Hadron Collider accelerator, to explore particle physics in unprecedented energy ranges. The FCC is a circular collider in a tunnel with a circumference of 80-100 km. The FCC study puts an emphasis on proton-proton high-energy and electron-positron high-intensity frontier machines. A proton-electron interaction scenario is also examined. According to the nominal FCC parameters, each of the 50 TeV proton beams will carry an amount of 8.5 GJ energy that is equivalent to the kinetic energy of an Airbus A380 (560 t) at a typical speed of 850 km /h . Safety of operation with such extremely energetic beams is an important issue, as off-nominal beam loss can cause serious damage to the accelerator and detector components with a severe impact on the accelerator environment. In order to estimate the consequences of an accident with the full beam accidently deflected into equipment, we have carried out numerical simulations of interaction of a FCC beam with a solid copper target using an energy-deposition code (fluka) and a 2D hydrodynamic code (big2) iteratively. These simulations show that, although the penetration length of a single FCC proton and its shower in solid copper is about 1.5 m, the full FCC beam will penetrate up to about 350 m into the target because of the "hydrodynamic tunneling." These simulations also show that a significant part of the target is converted into high-energy-density matter. We also discuss this interesting aspect of this study.

  16. RF properties of periodic accelerating structures for linear colliders

    International Nuclear Information System (INIS)

    With the advent of the SLAC electron-positron linear collider (SLC) in the 100 GeV center-of-mass energy range, research and development work on even higher energy machines of this type has started in several laboratories in the United States, Europe, the Soviet Union and Japan. These linear colliders appear to provide the only promising approach to studying e+e- physics at center-of-mass energies approaching 1 TeV. This thesis concerns itself with the study of radio frequency properties of periodic accelerating structures for linear colliders and their interaction with bunched beams. The topics that have been investigated are: experimental measurements of the energy loss of single bunches to longitudinal modes in two types of structures, using an equivalent signal on a coaxial wire to simulate the beam; a method of canceling the energy spread created within a single bunch by longitudinal wakefields, through appropriate shaping of the longitudinal charge distribution of the bunch; derivation of the complete transient beam-loading equation for a train of bunches passing through a constant-gradient accelerator section, with application to the calculation and minimization of multi-bunch energy spread; detailed study of field emission and radio frequency breakdown in disk-loaded structures at S-, C- and X-band frequencies under extremely high-gradient conditions, with special attention to thermal effects, radiation, sparking, emission of gases, surface damage through explosive emission and its possible control through RF-gas processing. 53 refs., 49 figs., 9 tabs

  17. Department of Energy assessment of the Large Hadron Collider

    International Nuclear Information System (INIS)

    This report summarizes the conclusions of the committee that assessed the cost estimate for the Large Hadron Collider (LHC). This proton-proton collider will be built at CERN, the European Laboratory for Particle Physics near Geneva, Switzerland. The committee found the accelerator-project cost estimate of 2.3 billion in 1995 Swiss francs, or about $2 billion US, to be adequate and reasonable. The planned project completion date of 2005 also appears achievable, assuming the resources are available when needed. The cost estimate was made using established European accounting procedures. In particular, the cost estimate does not include R and D, prototyping and testing, spare parts, and most of the engineering labor. Also excluded are costs for decommissioning the Large Electron-Positron collider (LEP) that now occupies the tunnel, modifications to the injector system, the experimental areas, preoperations costs, and CERN manpower. All these items are assumed by CERN to be included in the normal annual operations budget rather than the construction budget. Finally, contingency is built into the base estimate, in contrast to Department of Energy (DOE) estimates that explicitly identify contingency. The committee's charge, given by Dr. James F. Decker, Deputy Directory of the DOE Office of Energy Research, was to understand the basis for the LHC cost estimate, identify uncertainties, and judge the overall validity of the estimate, proposed schedule, and related issues. The committee met at CERN April 22--26, 1996. The assessment was based on the October 1995 LHC Conceptual Design Report or ''Yellow Book,'' cost estimates and formal presentations made by the CERN staff, site inspection, detailed discussions with LHC technical experts, and the committee members' considerable experience

  18. "2004 Beijing International Publishing Forum" to Be Held in Beijing

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

      The General Administration of Press & Publication and State Council Informa tion Office will host "2004 Beijing International Publishing Forum" prior to the Beijing International Book Fair this year (Aug.30-Sept.1, 2004) in Beijing Friendship Hotel,aiming to look into how to use international practices as reference in the current reform of publishing industry, to provide a dialogue and exchange platform for publishers and overseas leading publishing institutions, to learn advanced overseas publishing management philosophy and to further clear up our country's thinking of publishing industry reform and development.……

  19. "2004 Beijing International Publishing Forum" to Be Held in Beijing

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ The General Administration of Press & Publication and State Council Informa tion Office will host "2004 Beijing International Publishing Forum" prior to the Beijing International Book Fair this year (Aug.30-Sept.1, 2004) in Beijing Friendship Hotel,aiming to look into how to use international practices as reference in the current reform of publishing industry, to provide a dialogue and exchange platform for publishers and overseas leading publishing institutions, to learn advanced overseas publishing management philosophy and to further clear up our country's thinking of publishing industry reform and development.

  20. High-Mass Drell-Yan Cross-Section and Search for New Phenomena in Multi-Electron/Positron Final States with the ATLAS Detector

    CERN Document Server

    Wollstadt, Simon

    The Standard Model of particle physics is a very successful theory which describes nearly all known processes of particle physics very precisely. Nevertheless, there are several observations which cannot be explained within the existing theory. In this thesis, two analyses with high energy electrons and positrons using data of the ATLAS detector are presented. One, probing the Standard Model of particle physics and another searching for phenomena beyond the Standard Model. The production of an electron-positron pair via the Drell-Yan process leads to a very clean signature in the detector with low background contributions. This allows for a very precise measurement of the cross-section and can be used as a precision test of perturbative quantum chromodynamics (pQCD) where this process has been calculated at next-to-next-to-leading order (NNLO). The invariant mass spectrum $m_{ee}$ is sensitive to parton distribution functions (PFDs), in particular to the poorly known distribution of antiquarks at large moment...

  1. Optimizing electron-positron pair production on kilojoule-class high-intensity lasers for the purpose of pair-plasma creation

    International Nuclear Information System (INIS)

    Expressions for the yield of electron-positron pairs, their energy spectra, and production rates have been obtained in the interaction of multi-kJ pulses of high-intensity laser light interacting with solid targets. The Bethe-Heitler conversion of hard x-ray bremsstrahlung [D. A. Gryaznykh, Y. Z. Kandiev, and V. A. Lykov, JETP Lett. 67, 257 (1998); K. Nakashima and H. Takabe, Phys. Plasmas 9, 1505 (2002)] is shown to dominate over direct production (trident process) [E. P. Liang, S. C. Wilks, and M. Tabak, Phys. Rev. Lett. 81, 4887 (1998)]. The yields and production rates have been optimized as a function of incident laser intensity by the choice of target material and dimensions, indicating that up to 5x1011 pairs can be produced on the OMEGA EP laser system [L. J. Waxer et al., Opt. Photonics News 16, 30 (2005)]. The corresponding production rates are high enough to make possible the creation of a pair plasma.

  2. Measurement of Azimuthal Modulations in the Cross-Section of Di-Pion Pairs in Di-Jet Production from Electron-Positron Annihilation

    CERN Document Server

    Abdesselam, A; Adamczyk, K; Aihara, H; Said, S Al; Arinstein, K; Arita, Y; Asner, D M; Aso, T; Aulchenko, V; Aushev, T; Ayad, R; Aziz, T; Babu, V; Badhrees, I; Bahinipati, S; Bakich, A M; Bala, A; Ban, Y; Bansal, V; Barberio, E; Barrett, M; Bartel, W; Bay, A; Bedny, I; Behera, P; Belhorn, M; Belous, K; Bhardwaj, V; Bhuyan, B; Bischofberger, M; Biswal, J; Bloomfield, T; Blyth, S; Bobrov, A; Bondar, A; Bonvicini, G; Bookwalter, C; Bozek, A; Bračko, M; Breibeck, F; Brodzicka, J; Browder, T E; Červenkov, D; Chang, M -C; Chang, P; Chao, Y; Chekelian, V; Chen, A; Chen, K -F; Chen, P; Cheon, B G; Chilikin, K; Chistov, R; Cho, K; Chobanova, V; Choi, S -K; Choi, Y; Cinabro, D; Crnkovic, J; Dalseno, J; Danilov, M; Di Carlo, S; Dingfelder, J; Doležal, Z; Drásal, Z; Drutskoy, A; Dubey, S; Dutta, D; Dutta, K; Eidelman, S; Epifanov, D; Esen, S; Farhat, H; Fast, J E; Feindt, M; Ferber, T; Frey, A; Frost, O; Fujikawa, M; Fulsom, B G; Gaur, V; Gabyshev, N; Ganguly, S; Garmash, A; Getzkow, D; Gillard, R; Giordano, F; Glattauer, R; Goh, Y M; Golob, B; Perdekamp, M Grosse; Grygier, J; Grzymkowska, O; Guo, H; Haba, J; Hamer, P; Han, Y L; Hara, K; Hara, T; Hasegawa, Y; Hasenbusch, J; Hayasaka, K; Hayashii, H; He, X H; Heck, M; Hedges, M; Heffernan, D; Heider, M; Heller, A; Higuchi, T; Himori, S; Horiguchi, T; Hoshi, Y; Hoshina, K; Hou, W -S; Hsiung, Y B; Hsu, C -L; Huschle, M; Hyun, H J; Igarashi, Y; Iijima, T; Imamura, M; Inami, K; Inguglia, G; Ishikawa, A; Itagaki, K; Itoh, R; Iwabuchi, M; Iwasaki, M; Iwasaki, Y; Iwashita, T; Iwata, S; Jacobs, W W; Jaegle, I; Jones, M; Joo, K K; Julius, T; Kah, D H; Kakuno, H; Kang, J H; Kang, K H; Kapusta, P; Kataoka, S U; Katayama, N; Kato, E; Kato, Y; Katrenko, P; Kawai, H; Kawasaki, T; Kichimi, H; Kiesling, C; Kim, B H; Kim, D Y; Kim, H J; Kim, J B; Kim, J H; Kim, K T; Kim, M J; Kim, S H; Kim, S K; Kim, Y J; Kinoshita, K; Kleinwort, C; Klucar, J; Ko, B R; Kobayashi, N; Koblitz, S; Kodyš, P; Koga, Y; Korpar, S; Kouzes, R T; Križan, P; Krokovny, P; Kronenbitter, B; Kuhr, T; Kumar, R; Kumita, T; Kurihara, E; Kuroki, Y; Kuzmin, A; Kvasnička, P; Kwon, Y -J; Lai, Y -T; Lange, J S; Lee, D H; Lee, I S; Lee, S -H; Leitgab, M; Leitner, R; Lewis, P; Li, H; Li, J; Li, X; Li, Y; Gioi, L Li; Libby, J; Limosani, A; Liu, C; Liu, Y; Liu, Z Q; Liventsev, D; Loos, A; Louvot, R; Lukin, P; MacNaughton, J; Masuda, M; Matvienko, D; Matyja, A; McOnie, S; Mikami, Y; Miyabayashi, K; Miyachi, Y; Miyake, H; Miyata, H; Miyazaki, Y; Mizuk, R; Mohanty, G B; Mohanty, S; Mohapatra, D; Moll, A; Moon, H K; Mori, T; Moser, H -G; Müller, T; Muramatsu, N; Mussa, R; Nagamine, T; Nagasaka, Y; Nakahama, Y; Nakamura, I; Nakamura, K; Nakano, E; Nakano, H; Nakano, T; Nakao, M; Nakayama, H; Nakazawa, H; Nanut, T; Natkaniec, Z; Nayak, M; Nedelkovska, E; Negishi, K; Neichi, K; Ng, C; Niebuhr, C; Niiyama, M; Nisar, N K; Nishida, S; Nishimura, K; Nitoh, O; Nozaki, T; Ogawa, A; Ogawa, S; Ohshima, T; Okuno, S; Olsen, S L; Ono, Y; Onuki, Y; Ostrowicz, W; Oswald, C; Ozaki, H; Pakhlov, P; Pakhlova, G; Pal, B; Palka, H; Panzenböck, E; Park, C -S; Park, C W; Park, H; Park, H K; Park, K S; Peak, L S; Pedlar, T K; Peng, T; Pesantez, L; Pestotnik, R; Peters, M; Petrič, M; Piilonen, L E; Poluektov, A; Prasanth, K; Prim, M; Prothmann, K; Pulvermacher, C; Purohit, M; Reisert, B; Ribežl, E; Ritter, M; Röhrken, M; Rorie, J; Rostomyan, A; Rozanska, M; Ryu, S; Sahoo, H; Saito, T; Sakai, K; Sakai, Y; Sandilya, S; Santel, D; Santelj, L; Sanuki, T; Sasao, N; Sato, Y; Savinov, V; Schneider, O; Schnell, G; Schönmeier, P; Schram, M; Schwanda, C; Schwartz, A J; Schwenker, B; Seidl, R; Sekiya, A; Semmler, D; Senyo, K; Seon, O; Seong, I S; Sevior, M E; Shang, L; Shapkin, M; Shebalin, V; Shen, C P; Shibata, T -A; Shibuya, H; Shinomiya, S; Shiu, J -G; Shwartz, B; Sibidanov, A; Simon, F; Singh, J B; Sinha, R; Smerkol, P; Sohn, Y -S; Sokolov, A; Soloviev, Y; Solovieva, E; Stanič, S; Starič, M; Steder, M; Stypula, J; Sugihara, S; Sugiyama, A; Sumihama, M; Sumisawa, K; Sumiyoshi, T; Suzuki, K; Suzuki, S; Suzuki, S Y; Suzuki, Z; Takeichi, H; Tamponi, U; Tanaka, M; Tanaka, S; Tanida, K; Taniguchi, N; Tatishvili, G; Taylor, G N; Teramoto, Y; Tikhomirov, I; Trabelsi, K; Trusov, V; Tse, Y F; Tsuboyama, T; Uchida, M; Uchida, T; Uchida, Y; Uehara, S; Ueno, K; Uglov, T; Unno, Y; Uno, S; Urquijo, P; Ushiroda, Y; Usov, Y; Vahsen, S E; Van Hulse, C; Vanhoefer, P; Varner, G; Varvell, K E; Vervink, K; Vinokurova, A; Vorobyev, V; Vossen, A; Wagner, M N; Wang, C H; Wang, J; Wang, M -Z; Wang, P; Wang, X L; Watanabe, M; Watanabe, Y; Wedd, R; Wehle, S; White, E; Wiechczynski, J; Williams, K M; Won, E; Yabsley, B D; Yamada, S; Yamamoto, H; Yamaoka, J; Yamashita, Y; Yamauchi, M; Yashchenko, S; Ye, H; Yelton, J; Yook, Y; Yuan, C Z; Yusa, Y; Zhang, C C; Zhang, L M; Zhang, Z P; Zhao, L; Zhilich, V; Zhulanov, V; Ziegler, M; Zivko, T; Zupanc, A; Zwahlen, N; Zyukova, O

    2015-01-01

    We present an extraction of azimuthal correlations between two pairs of charged pions detected in opposite jets from electron-positron annihilation. These correlations may arise from the dependence of the di-pion fragmentation on the polarization of the parent quark in the process $e^+e^- \\rightarrow q \\bar{q}$. Due to the correlation of the quark polarizations, the cross-section of di-pion pair production, in which the pion pairs are detected in opposite jets in a dijet event, exhibits a modulation in the azimuthal angles of the planes containing the hadron pairs with respect to the production plane. The measurement of this modulation allows access to combinations of fragmentation functions that are sensitive to the quark's transverse polarization and helicity. Within our uncertainties we do not observe a significant signal from the previously unmeasured helicity dependent fragmentation function $G_1^\\perp$. This measurement uses a dataset of 938~fb$^{-1}$ collected by the Belle experiment at or near $\\sqrt{...

  3. Search for new physics in high mass electron-positron events in p anti-p collisions at s**(1/2) = 1.96-TeV

    Energy Technology Data Exchange (ETDEWEB)

    Aaltonen, T.; Abulencia, A.; Adelman, J.; Affolder, Anthony Allen; Akimoto, T.; Albrow, Michael G.; Amerio, S.; Amidei, Dante E.; Anastassov, A.; Anikeev, K.; Annovi, A. /Taiwan, Inst. Phys. /Argonne /Barcelona, IFAE /Baylor U. /INFN, Bologna /Bologna U. /Brandeis U. /UC, Davis /UCLA /UC, San Diego /UC, Santa Barbara

    2007-07-01

    We report the results of a search for a narrow resonance in electron-positron events in the invariant mass range of 150-950 GeV/c{sup 2} using 1.3 fb{sup -1} of p{bar p} collision data at {radical}s=1.96 TeV collected by the CDF II detector at Fermilab. No significant evidence of such a resonance is observed and we interpret the results to exclude the standard model-like Z{prime} with a mass below 923 GeV/c{sup 2} and the Randall-Sundrum graviton with a mass below 807 GeV/c{sup 2} for k/{bar M}{sub pl} = 0.1, both at the 95% confidence level. Combining with di-photon data excludes the Randall-Sundrum graviton for masses below 889 GeV/c{sup 2} for k/{bar M}{sub pl} = 0.1

  4. Development of prototype luminosity detector modules for future experiments on linear colliders

    CERN Document Server

    Kulis, Szymon

    The main objective of this dissertation is to develop and validate the prototype module of the LumiCal luminosity detector. The dissertation presents the works executed from the first detector concept, through all subsequent R&D stages, ending with the test beam results obtained using the complete detector module. Firstly, the linear electron positron colliders and planned experiments are introduced, together with their role in our understanding of the basis of matter and sensing for the New Physics. The signal extraction from radiation sensors and further signal processing techniques are discussed in chapter 2. Besides the commonly accepted techniques of amplitude and time measurements, a novel readout implementation, utilizing digital signal processing and deconvolution principle, is proposed, and its properties are analyzed in details. The architecture, design, and measurements of the LumiCal readout chain components are presented in chapter 3. A dedicated test setups prepared for their parameterizatio...

  5. Experience of operating the large vacuum system of the KEKB collider. High stored current issues

    International Nuclear Information System (INIS)

    For the KEK B-factory, an electron-positron collider which consists of two storage rings intersecting at the collision point has been running in operation since December 1998. The ring has a circumference of 3016 m, and its vacuum chambers are mainly made of copper. Until July 2001, a fill with the initial current of 940 mA positron and 730 mA electron was established and the world record luminosity was achieved. Before the goal currents of 2.6 A positron and 1.1 A electron are achieved, the effect of high beam current has been emerging. The effect of electron cloud became evident especially in the LER. Some bellows were found to be warmed by the TE mode of beam induced fields. Direct damage by beam is seen at the surface of the movable mask. An indirect effect of the high beam current passing close to a vacuum seal is also observed. (author)

  6. Anomalous WWγ couplings with beam polarization at the Compact Linear Collider

    Science.gov (United States)

    Arı, V.; Billur, A. A.; İnan, S. C.; Köksal, M.

    2016-05-01

    We study the anomalous WWγ couplings at the Compact Linear Collider through the processes e+e- →W+W-, e-e+ →e-γ*e+ →e+νeW- and e-e+ →e-γ*γ*e+ →e-W+W-e+ (γ* is the Weizsacker-Williams photon). We give the 95% confidence level limits for unpolarized and polarized electron (positron) beam on the anomalous couplings for various values of the integrated luminosities and center-of-mass energies. We show that the obtained limits on the anomalous couplings through these processes can highly improve the current experimental limits. In addition, our limits with beam polarization are approximately two times better than the unpolarized case.

  7. LEP the lord of the collider rings at CERN 1980-2000

    CERN Document Server

    Schopper, Herwig Franz

    2009-01-01

    Housed by a 4 m diameter tunnel of 27 km circumference, with huge underground labs and numerous surface facilities, and set up with a precision of 0.1 mm per kilometer, the Large Electron-Positron Collider (LEP) was not only the largest but also one of the most sophisticated scientific research instrument ever created by Man. Located at CERN, near Geneva, LEP was built during the years 1983 - 1989, was operational until 2000, and corroborated the standard model of particle physics through continous high precision measurements. The Author, director-general of CERN during the crucial period of the construction of LEP, recounts vividly the convoluted decision-making and technical implementation processes - the tunnel alone being a highly challenging geo- and civil engineering project - and the subsequent extremely fruitful period of scientific research. Finally he describes the difficult decision to close down LEP, at a time when the discovery of the Higgs boson seemed within reach. LEP was eventually dismantled...

  8. Precision Studies of Hadronic and Electro-Weak Interactions for Collider Physics. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Yost, Scott A [The Citadel, Charleston, SC (United States)

    2014-04-02

    This project was directed toward developing precision computational tools for proton collisions at the Large Hadron Collider, focusing primarily on electroweak boson production and electroweak radiative corrections. The programs developed under this project carried the name HERWIRI, for High Energy Radiation With Infra-Red Improvements, and are the first steps in an ongoing program to develop a set of hadronic event generators based on combined QCD and QED exponentiation. HERWIRI1 applied these improvements to the hadronic shower, while HERWIRI2 will apply the electroweak corrections from the program KKMC developed for electron-positron scattering to a hadronic event generator, including exponentiated initial and final state radiation together with first-order electroweak corrections to the hard process. Some progress was also made on developing differential reduction techniques for hypergeometric functions, for application to the computation of Feynman diagrams.

  9. Electrodynamic processes on the colliding beams and electric dipole moments of leptons

    International Nuclear Information System (INIS)

    The cross sections of the esup(+-) + e-→ esup(+-) + e-, e+ + e- → μ+ + μ- processes have been calculated with regard to possible electric dipole moments of leptons. Estimates for the electron and muon electric dipole moments at great transferred momenta q2 (both space-line and time-line) are found with the use of results of experiments on the colliding electron-positron beams; the experiments were carried out with the purpose of testing quantum electrodynamics. The muon dipole moment cannot exceed 5x1016-e x cm at q2=25(GeV)2. The following estimates are found for the anapole moment of electron (αsub(e)) and muon (αsub(μ)) at the same value of q2 : αsub(e)-9 e/μ2, αsub(μ)-4e/μ2; m(μ) is the electron(muon) mass

  10. Higgs physics at a high luminosity e+e- linear collider

    CERN Document Server

    Sopczak, André

    2002-01-01

    Since the TESLA Technical Design Report (TDR) was published in 2001, the physics programme of an electron-positron linear collider (LC) has been further developed and a wide consensus has been reached on the physics case and the need for a high luminosity LC with center-of-mass energy up to about 1 TeV as the next worldwide high-energy physics project. The study of the Higgs boson properties represents a significant part of this physics programme. New studies demonstrate that a LC providing 1000 fb-1 of data at center-of-mass energies of at least 500 GeV, is an excellent Higgs boson analyzer for a wide range of masses. A summary of preliminary results of these studies and their implications for identifying the nature of the Higgs sector and for constraining the parameter space of extended models is given. The focus is on recent developments and the relation to the LHC is addressed.

  11. Experimental Measurements of e-Cloud Mitigation Using Clearing Electrodes in the DAФNE Collider

    CERN Document Server

    Alesini, D; Gallo, A; Guiducci, S; Milardi, C; Zobov, M; De Santis, S; Demma, Theo; Raimondi, P

    2012-01-01

    Recently the DAФNE electron-positron collider has started delivering luminosity to the KLOE-2 experiment. For this run special metallic electrodes were installed in all the dipole and wiggler magnets of the positron ring to cope with the effects induced by the e-cloud formation. Experimental measurements have shown an impressive effectiveness of these devices in mitigating the e-cloud impact on the positron beam dynamics. The electrodes allow reducing the vertical beam size and the growth rate of transverse instabilities as well as the tune shifts induced by the electron cloud itself. Moreover frequency shift measurements of the vacuum chamber resonances, switching on and off the electrodes, indicate an evident reduction of the electron cloud density. This paper reports and analyses all the experimental observations and measurements done to suppress the e-cloud induced effects by using metallic electrodes.

  12. Fourth Beijing Human Rights Forum Held in Beijing

    Institute of Scientific and Technical Information of China (English)

    OUR STAFF REPORTER

    2012-01-01

    The Fourth Beijing Forum on Human Rights was held in Beijing from September 21-23,2011.Jointly sponsored by the China Society for Human Rights Studies and the China Human Rights Development Foundation,the forum was centered on the theme of "Cultural Tradition,Concept of Values and Human Rights." Attending were nearly 100senior human rights officials,specialists and scholars from 26 countries and regions as well as the United Nations and other international organizations.

  13. Beijing restaurant network

    Science.gov (United States)

    Fu, Chun-Hua; Zhnag, Pei-Fang; Wang, Yong-Li; Shi, Jian-Jun; Feng, Ai-Xia; He, Da-Ren

    2008-03-01

    We have empirically studied the restaurants in Beijing and suggested a network description on the system. We define the restaurants as nodes and connect a link between two nodes if the two restaurants sell a common dish. The edge represents the sale competition relationship. In order to describe the competition, we define a node weight, which is the mark given by consumers on an evaluation network (http://www.dianping.com), to the restaurant in cooking the dish. 3338 nodes and 688 dishes have been investigated. We find that both the total node weight, which is defined as the sum of the node weight in all the dishes, and the so-called dish weight, which is defined as the sum of the node weight in one dish, show a rather nice power law distribution.

  14. Rethinking the Beijing Consensus

    DEFF Research Database (Denmark)

    Jiang, Yang

    2011-01-01

    proposed by the Chinese leadership. A prominent feature of China's responses to the crisis is a bias towards state-owned enterprises and the public sector, which exacerbates the existing problems of monopoly, over-capacity, inequality, the regulators being ‘captured’ by industrial interests and...... protectionism. Given limited economic resources, domestic political contentions and the questionable credibility of the China Model, it would be difficult for China to practice ‘responsible great power’ diplomacy or assume leadership in the region or globally.......This paper discusses the role of the Beijing Consensus type of foreign and economic policymaking in China's development since the Asian financial crisis and in its response to the global crisis, and argues that it has been a double-edged sword, as reflected in several aspects. First, the lesson...

  15. Why Overseas Moguls Choose Beijing

    Institute of Scientific and Technical Information of China (English)

    LIJINGXIA

    2003-01-01

    TODAY,China is an area of strategic significance to tofreign businesses.World IT giants like Bill Gates,Scott McNealy,and Michael Dell all formulated their individual development strategies after visiting China.Gates is soon to invest substantially in establishing a Chinese base,McNealy is jockeying for a bigger piece of the Chinese market,and Michael Dell has expressed his intention to make China a crucial link within his global strategy.These facts confirm China's position within transnational corporate global strategy.To date,a total 20 transnational corporations have chosen Beijing as their regional headquarters,and among the top 500 transnational corporations,160 have invested in Beijing.What is it about Beijing that so draws international investors?And what impression do they have of Beijing?

  16. New Luxury in Regal Beijing

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Beijing is a city where informationpours in from all over the world,where international brands are set amongst beautiful traditions. Here prosperity is promised, and a successful new generation is creating its own trends, cultures and values. For these pioneers of style and individuality, the LG Beijing Tower is poised to provide a place to work, shop and interact in an environment that embodies new trends and sophistication.

  17. Comparison of three-jet and radiative two-jet events in electron-positron annihilation at 29 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Sheldon, P.D.

    1986-11-01

    By comparing 3-jet (e/sup +/e/sup -/ ..-->.. q anti q g) and radiative 2-jet (e/sup +/e/sup -/ ..-->.. q anti q ..gamma..) events from electron-positron annihilation, we have studied the local and global effects of the presence of a hard bremsstrahlung gluon in hadronic events. Detector and event selection efficiencies and biases affect these two kinds of events almost equally because they have very similar kinematics and topologies. Accurate comparisons of q anti q g and q anti q ..gamma.. events can therefore be made. Globally, we observe a depletion of hadrons in q anti q g events relative to q anti q ..gamma.. events on the opposite side of the event plane from the gluon, in the angular region between the q and anti q jets. This depletion is shown to be in agreement with the predictions of Quantum Chromodynamics (QCD). The existence of this effect demonstrates that the presence of a gluon significantly alters the color forces and hence the fragmentation process in hadronic events. We also use these q anti q ..gamma.. and q anti q g events to compare low energy (4.5 GeV) gluon and quark jets. Our data indicate that gluon jets have softer x/sub p/ distributions than quark jets, while the transverse momentum distributions of these two types of jets are identical within our errors. Although we are unable to determine if the multiplicities of gluon (n/sub /) and quark (n/sub q/) jets are different, the ratio n/sub g//n/sub q/ = 9/4 predicted asymptotically in QCD would not be consistent with our data.

  18. Linear collider: a preview

    Energy Technology Data Exchange (ETDEWEB)

    Wiedemann, H.

    1981-11-01

    Since no linear colliders have been built yet it is difficult to know at what energy the linear cost scaling of linear colliders drops below the quadratic scaling of storage rings. There is, however, no doubt that a linear collider facility for a center of mass energy above say 500 GeV is significantly cheaper than an equivalent storage ring. In order to make the linear collider principle feasible at very high energies a number of problems have to be solved. There are two kinds of problems: one which is related to the feasibility of the principle and the other kind of problems is associated with minimizing the cost of constructing and operating such a facility. This lecture series describes the problems and possible solutions. Since the real test of a principle requires the construction of a prototype I will in the last chapter describe the SLC project at the Stanford Linear Accelerator Center.

  19. Concept of a software trigger for an experiment at the TESLA linear collider

    CERN Document Server

    Eckerlin, G; Heuer, R D; Le Dû, P; Quast, G

    2000-01-01

    TESLA is one of the design proposals for a TeV range linear electron positron collider. Electrons and positrons are grouped in bunch trains which collide with a rate of 5 Hz. Each train itself consists out of 2820 bunches with a bunch to bunch distance of 337 ns giving 2820 possible collisions in 950 mus followed by 199 ms without any interaction. This operation mode requires a deadtime free data taking within 1 ms but leaves 200 ms afterwards for reading the data before the next trains will collide. In conjunction with the aim of being able to select rare and maybe as yet unknown event topologies it gives rise to the proposal of a pure software trigger concept in the proposed detector design. All detector signals are digitized and stored in buffers for each collision prior to event building via a fast network. All bunches are then analyzed in a processor farm and classified in various streams from interesting physics to background, monitoring and calibration events. Finally, all events are stored in appropri...

  20. Hadron hadron collider group

    International Nuclear Information System (INIS)

    The objective of this group was to make a rough assessment of the characteristics of a hadron-hadron collider which could make it possible to study the 1 TeV mass scale. Since there is very little theoretical guidance for the type of experimental measurements which could illuminate this mass scale, we chose to extend the types of experiments which have been done at the ISR, and which are in progress at the SPS collider to these higher energies

  1. FERMILAB: Collider detectors -2

    International Nuclear Information System (INIS)

    Last month's edition (April, page 12) included a status report on data collection and preliminary physics results from the 'newcomer' DO detector at Fermilab's Tevatron proton-antiproton collider. This time the spotlight falls in the Veteran' CDF detector, in action since 1985 and meanwhile significantly upgraded. Meanwhile the Tevatron collider continues to improve, with record collision rates

  2. Haze over Beijing

    Science.gov (United States)

    2007-01-01

    Thick haze collected over the Beijing region in late March 2007. Earlier that month, the BBC News reported that an international team of scientists had documented how increasing pollution in China led to decreasing rainfall over the region. The Moderate Resolution Imaging Spectroradiometer (MODIS) flying onboard the Aqua satellite captured these images of the Beijing region on March 22, 2007. The top image is a 'true-color' picture, similar to a digital photo. The bottom, 'false-color,' image uses a combination of visible and infrared light to more clearly show vegetation, water, and clouds. Even sparse vegetation appears bright green, while water appears deep blue (bright blue when tinged with sediment). Clouds dominated by water droplets appear white, while clouds made of ice crystals appear light blue. The false-color image highlights water bodies, perhaps aqua-culture ponds, that are all but invisible in the true-color image, especially along the shores of the Bo Hai. While vegetation and water show up more clearly in the false-color image, haze is much more transparent. Although dingy gray haze dominates the true-color picture, it is all but invisible in the false-color view. The haze 'disappears' in the infrared-enhanced image because tiny haze particles do not reflect longer-wavelength infrared light very well, making this type of image useful for distinguishing haze from clouds. The bank of clouds in the upper right corner shows up clearly in both pictures. As China industrializes, factories, power plants, and automobiles all contribute to pollution in the region. In examining pollutants and rainfall, the team of scientists examined records covering more than 50 years, concluding that pollution decreased precipitation at Mount Hua near Xi'an in central China. They concluded that when conditions are so hazy that visibility is reduced to less than 8 kilometers (5 miles), hilly precipitation can drop by 30 to 50 percent. When moist air passes over mountains

  3. Photon collider at TESLA

    International Nuclear Information System (INIS)

    High energy photon colliders (γγ, γe) based on backward Compton scattering of laser light is a very natural addition to e+e- linear colliders. In this report, we consider this option for the TESLA project. Recent study has shown that the horizontal emittance in the TESLA damping ring can be further decreased by a factor of four. In this case, the γγ luminosity in the high energy part of spectrum can reach about (1/3)Le+e-. Typical cross-sections of interesting processes in γγ collisions are higher than those in e+e- collisions by about one order of magnitude, so the number of events in γγ collisions will be more than that in e+e- collisions. Photon colliders can, certainly, give additional information and they are the best for the study of many phenomena. The main question is now the technical feasibility. The key new element in photon colliders is a very powerful laser system. An external optical cavity is a promising approach for the TESLA project. A free electron laser is another option. However, a more straightforward solution is ''an optical storage ring (optical trap)'' with a diode pumped solid state laser injector which is today technically feasible. This paper briefly reviews the status of a photon collider based on the linear collider TESLA, its possible parameters and existing problems

  4. Photon collider at TESLA

    Science.gov (United States)

    Telnov, Valery

    2001-10-01

    High energy photon colliders ( γγ, γe) based on backward Compton scattering of laser light is a very natural addition to e +e - linear colliders. In this report, we consider this option for the TESLA project. Recent study has shown that the horizontal emittance in the TESLA damping ring can be further decreased by a factor of four. In this case, the γγ luminosity in the high energy part of spectrum can reach about (1/3) Le +e -. Typical cross-sections of interesting processes in γγ collisions are higher than those in e +e - collisions by about one order of magnitude, so the number of events in γγ collisions will be more than that in e +e - collisions. Photon colliders can, certainly, give additional information and they are the best for the study of many phenomena. The main question is now the technical feasibility. The key new element in photon colliders is a very powerful laser system. An external optical cavity is a promising approach for the TESLA project. A free electron laser is another option. However, a more straightforward solution is "an optical storage ring (optical trap)" with a diode pumped solid state laser injector which is today technically feasible. This paper briefly reviews the status of a photon collider based on the linear collider TESLA, its possible parameters and existing problems.

  5. Giovanni Arrighi in Beijing

    Directory of Open Access Journals (Sweden)

    Ganesh Trichur

    2015-08-01

    Full Text Available Giovanni Arrighi's Adam Smith in Beijing (ASB subverts the temporality and conceptual vocabulary employed by most writers working in a Marxist tradition. In this view, capitalism is a mode of production which eventually encompasses the entire world. Perhaps it began in England and expanded from there. Perhaps its expansion through colonial empires should be seen as part of its constitution, rather than an after effect (i.e. the perspective of Wallerstein. In any case, it eventually dominates the world and every place that is a part of it through such phenomena as, multinational corporations, wage labor, and international capital flows. The particular class relations, political systems, and international relations that held before the spread of capitalism are only of interest to the extent that they leave a residue which may be reclaimed by actors seeking to reinforce or undermine the rule of capital in particular places. For Arrighi, Chinese development neither is, nor ever was, simply “capitalist.” Rather, it was, and continues to be “Smithian,” devoted to the maintenance and expansion of a market society (the obvious irony here is that China is seen as more “Smithian” than those places which most heartily celebrate the Scottish political economist.

  6. Electron-Positron Accumulator (EPA)

    CERN Multimedia

    Photographic Service

    1986-01-01

    After acceleration in the low-current linac LIL-W, the electrons and positrons are accumulated in EPA to obtain a sufficient intensity and a suitable time-structure, before being passed on to the PS for further acceleration to 3.5 GeV. Electrons circulate from right to left, positrons in the other direction. Dipole bending magnets are red, focusing quadrupoles blue, sextupoles for chromaticity-control orange. The vertical tube at the left of the picture belongs to an optical transport system carrying the synchrotron radiation to detectors for beam size measurement. Construction of EPA was completed in spring 1986. LIL-W and EPA were conceived for an energy of 600 MeV, but operation was limited to 500 MeV.

  7. Computer and network applications in beam measurement system of accelerator

    International Nuclear Information System (INIS)

    The applications of computer and its network in beam measurement system for Beijing Electron Positron Collider (BEPC) are described. It includes the instrumentation interfaces, the hardware and software implementations for the network connection between microcomputers and VAX series minicomputers. The communication program using Windows socket, a network programming interface for Microsoft Windows, are also described

  8. Measurements of Cabibbo Suppressed Hadronic Decay Fractions of Charmed D0 and D+ Mesons

    OpenAIRE

    BES Collaboration

    2005-01-01

    Using data collected with the BESII detector at $e^{+}e^{-}$ storage ring Beijing Electron Positron Collider, the measurements of relative branching fractions for seven Cabibbo suppressed hadronic weak decays $D^0 \\to K^- K^+$, $\\pi^+ \\pi^-$, $K^- K^+ \\pi^+ \\pi^-$ and $\\pi^+ \\pi^+ \\pi^- \\pi^-$, $D^+ \\to \\bar{K^0} K^+$, $K^- K^+ \\pi^+$ and $\\pi^- \\pi^+ \\pi^+$ are presented.

  9. Implementation of experimental physics and industrial control system on Linux platform

    International Nuclear Information System (INIS)

    The paper describes the system structure and implementation of experimental physics and industrial control system (EPICS) on Linux platform. The implementation provides an alternative operating system for the upgrade of Beijing electron positron collider control system. It also provides a new thought for using the EPICS in control systems of other fields

  10. Private Museums Gain Popularity in Beijing

    Institute of Scientific and Technical Information of China (English)

    Staff; Wangfeng

    2003-01-01

    "Have you ever been to a private museum?" The question pops upregularly in conversations here,indicating that smaller, specialized museums have become a valued partof Beijing cultural life. The trendstarted with the Beijing Guan Fu Classical Art Museum,

  11. 15th Beijing International Book Fair

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The 15th Beijing Intemational Book Fair(BIBF)is to be held in Tianjin on September 1-4.It is the first time that the fair is held outside of Beijing. The change of venue is because the book fair coincides with the closing of the Beijing Olympic Games and the open-

  12. COLLIDE Pro Helvetia Award

    CERN Multimedia

    2016-01-01

    The COLLIDE Pro Helvetia Award is run in partnership with Pro Helvetia, giving the opportunity to Swiss artists to do research at CERN for three months.   From left to right: Laura Perrenoud, Marc Dubois and Simon de Diesbach. The photo shows their VR Project, +2199. Fragment.In are the winning artists of COLLIDE Pro Helvetia. They came to CERN for two months in 2015, and will now continue their last month in the laboratory. Fragment.In is a Swiss based interaction design studio. They create innovative projects, interactive installations, video and game design. Read more about COLLIDE here.

  13. Superconducting super collider

    International Nuclear Information System (INIS)

    The Superconducting Super Collider is to be a 20 TeV per beam proton-proton accelerator and collider. Physically the SCC will be 52 miles in circumference and slightly oval in shape. The use of superconducting magnets instead of conventional cuts the circumference from 180 miles to the 52 miles. The operating cost of the SCC per year is estimated to be about $200-250 million. A detailed cost estimate of the project is roughly $3 billion in 1986 dollars. For the big collider ring, the technical cost are dominated by the magnet system. That is why one must focus on the cost and design of the magnets. Presently, the process of site selection is underway. The major R and D efforts concern superconducting dipoles. The magnets use niobium-titanium as a conductor stabilized in a copper matrix. 10 figures

  14. The Large Hadron Collider

    CERN Document Server

    Evans, Lyndon

    2012-01-01

    The construction of the Large Hadron Collider (LHC) has been a massive endeavour spanning almost 30 years from conception to commissioning. Building the machine with the highest possible energy (7 TeV) in the existing large electron–positron (LEP) collider tunnel of 27 km circumference and with a tunnel diameter of only 3.8 m has required considerable innovation. The first was the development of a two-in-one magnet, where the two rings are integrated into a single magnetic structure. This compact two-in-one structure was essential for the LHC owing to the limited space available in the existing LEP collider tunnel and the cost. The second was a bold move to the use of superfluid helium cooling on a massive scale, which was imposed by the need to achieve a high (8.3 T) magnetic field using an affordable Nb-Ti superconductor.

  15. The Days Hotel & Suites Beijing

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A Cultural Concept Located within striking distance of Beijing's booming Central Business District, the Days Hotel & Suites Beijing also offers easy access to the art of the imperial city. Adjacent to the Panjiayuan Flea Market, where curios and folk artworks of the ancient capital are bought and traded, it is a multi-function concept of fine dining and entertainment that taps into the cultural essence of China's storied past. In the entrance to the sizeable lobby of Regal Palace Chinese Cuisine House, a...

  16. Photon collider at TESLA

    OpenAIRE

    Telnov, Valery

    2000-01-01

    High energy photon colliders (gamma-gamma, gamma-electron) based on backward Compton scattering of laser light is a very natural addition to e+e- linear colliders. In this report we consider this option for the TESLA project. Recent study has shown that the horizontal emittance in the TESLA damping ring can be further decreased by a factor of four. In this case the gamma-gamma luminosity luminosity in the high energy part of spectrum can reach (1/3)L_{e+e-}. Typical cross sections of interest...

  17. The Muon Collider

    International Nuclear Information System (INIS)

    We describe the scientific motivation for a new type of accelerator, the muon collider. This accelerator would permit an energy-frontier scientific program and yet would fit on the site of an existing laboratory. Such a device is quite challenging, and requires a substantial R and D program. After describing the ingredients of the facility, the ongoing R and D activities of the Muon Accelerator Program are discussed. A possible U.S. scenario that could lead to a muon collider at Fermilab is briefly mentioned.

  18. Muon collider design

    International Nuclear Information System (INIS)

    The possibility of muon colliders was introduced by Skrinsky et al., Neuffer, and others. More recently, several workshops and collaboration meetings have greatly increased the level of discussion. In this paper we present scenarios for 4 TeV and 0.5 TeV colliders based on an optimally designed proton source, and for a lower luminosity 0.5 TeV demonstration based on an upgraded version of the AGS. It is assumed that a demonstration version based on upgrades of the FERMILAB machines would also be possible. 53 refs., 25 figs., 8 tabs

  19. Collide@CERN Geneva

    CERN Document Server

    CERN. Geneva; Kieffer, Robert; Blas Temino, Diego; Bertolucci, Sergio; Mr. Decelière, Rudy; Mr. Hänni, Vincent

    2014-01-01

    CERN, the Republic and Canton of Geneva, and the City of Geneva are delighted to invite you to “Collide@CERN Geneva Music”. Come to the public lecture about collisions between music and particle physics by the third winners of Collide@CERN Geneva, Vincent Hänni & Rudy Decelière, and their scientific inspiration partners, Diego Blas and Robert Kieffer. The event marks the beginning of their residency at CERN, and will be held at the CERN Globe of Science and Innovation on 16 October 2014 at 19.00. Doors will open at 18.30.

  20. Madgraph School 2013 Beijing

    CERN Document Server

    2013-01-01

    The Monte-Carlo tools play an indispensable role for our understanding to the subatomic structure, among them the Madgraph/Madevent package is a popular and interface-friendly one which is favored by more than 1000 physicists, both theorists and experimentalists. We organize a 5-day school from 22/May/2013 to 26/May/2013 to introduce the most relevant physics at the LHC. By using Madgraph/Madevent package as a focus example, the school will expose the core structure on the Monte Carlo simulation techniques at the LHC. There are 15 lectures and extra 10 tutorial sessions in total for students to finish the exercising projects in groups. Lectures will cover the main parts of Monte Carlo techniques: Feynrules, Madgraph, Sherpa, Fastjet, and PGS/DELPHES as well as experimental statistics. Students, postdoctors, and young researchers, who are working on collider physics, are encouraged to participate this school. No registration fee is required. We will provide local expenses for the participants, including a...

  1. Construction and testing of a large scale prototype of a silicon tungsten electromagnetic calorimeter for a future lepton collider

    International Nuclear Information System (INIS)

    The CALICE collaboration is preparing large scale prototypes of highly granular calorimeters for detectors to be operated at a future linear electron positron collider. After several beam campaigns at DESY, CERN and FNAL, the CALICE collaboration has demonstrated the principle of highly granular electromagnetic calorimeters with a first prototype called physics prototype. The next prototype, called technological prototype, addresses the engineering challenges which come along with the realisation of highly granular calorimeters. This prototype will comprise 30 layers where each layer is composed of four 9×9 cm2 silicon wafers. The front end electronics is integrated into the detector layers. The size of each pixel is 5×5 mm2. This prototype enters its construction phase. We present results of the first layers of the technological prototype obtained during beam test campaigns in spring and summer 2012. According to these results the signal over noise ratio of the detector exceeds the R and D goal of 10:1

  2. Hadron collider physics

    International Nuclear Information System (INIS)

    An introduction to the techniques of analysis of hadron collider events is presented in the context of the quark-parton model. Production and decay of W and Z intermediate vector bosons are used as examples. The structure of the Electroweak theory is outlined. Three simple FORTRAN programs are introduced, to illustrate Monte Carlo calculation techniques. 25 refs

  3. High luminosity particle colliders

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, R.B.; Gallardo, J.C. [Brookhaven National Lab., Upton, NY (United States). Center for Accelerator Physics

    1997-03-01

    The authors consider the high energy physics advantages, disadvantages and luminosity requirements of hadron (pp, p{anti p}), lepton (e{sup +}e{sup {minus}}, {mu}{sup +}{mu}{sup {minus}}) and photon-photon colliders. Technical problems in obtaining increased energy in each type of machine are presented. The machines relative size are also discussed.

  4. High energy colliders

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, R.B.; Gallardo, J.C. [Brookhaven National Lab., Upton, NY (United States). Center for Accelerator Physics

    1997-02-01

    The authors consider the high energy physics advantages, disadvantages and luminosity requirements of hadron (pp, p{anti p}), lepton (e{sup +}e{sup {minus}}, {mu}{sup +}{mu}{sup {minus}}) and photon-photon colliders. Technical problems in obtaining increased energy in each type of machine are presented. The machines relative size are also discussed.

  5. The Large Hadron Collider

    CERN Multimedia

    't Hooft, Gerardus; Llewellyn Smith, Christopher Hubert; Brüning, Oliver Sim; Collier, Paul; Stapnes, Steinar; Ellis, Jonathan Richard; Braun-Munzinger, Peter; Stachel, Johanna; Lederman, Leon Max

    2007-01-01

    Several articles about the LHC: The Making of the standard model; high-energy colliders and the rise of the standard model; How the LHC came to be; Building a behemoth; Detector challenges at the LHC; Beyond the standard model with the LHC; The quest for the quark-gluon plasma; The God particle et al. (42 pages

  6. High energy colliders

    International Nuclear Information System (INIS)

    The authors consider the high energy physics advantages, disadvantages and luminosity requirements of hadron (pp, p anti p), lepton (e+e-, μ+μ-) and photon-photon colliders. Technical problems in obtaining increased energy in each type of machine are presented. The machines relative size are also discussed

  7. Photon collider at TESLA

    CERN Document Server

    Telnov, V I

    2001-01-01

    High energy photon colliders (gamma-gamma, gamma-electron) based on backward Compton scattering of laser light is a very natural addition to e+e- linear colliders. In this report we consider this option for the TESLA project. Recent study has shown that the horizontal emittance in the TESLA damping ring can be further decreased by a factor of four. In this case the gamma-gamma luminosity luminosity in the high energy part of spectrum can reach 0.3--0.5 L_{e+e-}. Typical cross sections of interesting processes in gamma-gamma collisions are higher than those in e+e- collisions by about one order of magnitude, so the number of events in gamma-gamma collisions will be more that in e+e- collisions. Photon colliders can, certainly, give additional information and they are the best for the study of many phenomena. The main question is now the technical feasibility. The key new element in photon colliders is a very powerful laser system. An external optical cavity is a promising approach for the TESLA project. A free...

  8. Tevatron's complex collider cousins

    CERN Multimedia

    Fischer, W

    2004-01-01

    Letter referring to Schwarzschild's story "Disappointing performance and tight budgets confront Fermilab with tough decisions" and contesting that the Tevatron is not the most complex accelerator operating. They use the examples of CERN's SPS collider, HERA at DESY and the RHIC at Brookhaven (1/4 page)

  9. Hadron collider physics

    Energy Technology Data Exchange (ETDEWEB)

    Pondrom, L.

    1991-10-03

    An introduction to the techniques of analysis of hadron collider events is presented in the context of the quark-parton model. Production and decay of W and Z intermediate vector bosons are used as examples. The structure of the Electroweak theory is outlined. Three simple FORTRAN programs are introduced, to illustrate Monte Carlo calculation techniques. 25 refs.

  10. Large Hadron Collider

    CERN Multimedia

    2007-01-01

    "In the spring 2008, the Large Hadron Collider (LHC) machine at CERN (the European Particle Physics laboratory) will be switched on for the first time. The huge machine is housed in a circular tunnel, 27 km long, excavated deep under the French-Swiss border near Geneva." (1,5 page)

  11. Superconducting Super Collider project

    International Nuclear Information System (INIS)

    The scientific need for the Superconducting Super Collider (SSC) is outlined, along with the history of the development of the SSC concept. A brief technical description is given of each of the main points of the SSC conceptual design. The construction cost and construction schedule are discussed, followed by issues associated with the realization of the SSC. 8 refs., 3 figs., 3 tabs

  12. Beijing Star Lake Ecology Park

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Beijing Star Lake Ecology Park is a Five-star hotel which has developed multi-functions of restaurant, lodge, bath, landscape seeing, leisure,body exercise, recreation, Ecology agriculture,etc. Occupying an area of 500 mu, the park is an environmental friendly five-star hotel.

  13. Olympic Effect on Beijing Logistics

    Institute of Scientific and Technical Information of China (English)

    Guo Liqin

    2008-01-01

    @@ Olympic logistics network as preparationIn 2003, the Beijing municipal government proposed the blueprint for three key logistics projects for the 2008 Olympics. It planned to build three logistics bases (at Yancun in Fangshan District, Majuqiao in Tongzhou, and Shahe in Changping District) along with four logistics centers (at Tianzhu in Chaoyang, Shibajiadian in Chaoyang, Dazhuang in Daxing, and Mentougou).

  14. Beijing +5 Review Outcome Document

    OpenAIRE

    United Nations, UN

    2000-01-01

    The Beijing +5 Outcome Document strengthened commitments to eradicate harmful traditional practices, including so called 'honour killings', forced marriages and female genital mutilation. Among other things, it also called upon governments to eliminate gender discriminatory legislation by 2005 and create greater access to affordable treatment and care for women and girls living with HIV and AIDS.

  15. Sound Security,Safe Beijing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ With the approach of the long a waited event,Chinese authorities have geared up to intensify security preparations.In line with the"people-oriented"and"athletes-centered"ideas,Beijing will spare no efforts to provide quality services and to build a safe and cornfort able environment that will satisfy all the Games' participants.

  16. Beijing Opera Percussion Pattern Dataset

    OpenAIRE

    CompMusic

    2016-01-01

    Beijing Opera Percussion Pattern (BOPP) dataset is a collection of 133 audio percussion patterns covering five pattern classes. The dataset includes the audio and syllable level transcriptions for the patterns (non-time aligned). It is useful for percussion transcription and classification tasks. The patterns have been extracted from audio recordings of arias and labeled by a musicologist.

  17. Bars in Beijing Old Town

    Institute of Scientific and Technical Information of China (English)

    GUANYUNZHANG

    2003-01-01

    It's seven pm on a summer's evening by Shichahao Lake,central Beijing.A welcome breeze whispers across the lake,and the ruddy vestiges of sunset linger on roofs and treetops.A low hum emanates from bars on the lakeshore packed with young people chatting,drinking and generally

  18. Beijing: Beyond the Olympic city

    NARCIS (Netherlands)

    Chen, Y.

    2012-01-01

    Mega-event strategies have become part of a deliberate urban policy for cities around the world. There is a particular concern on how to combine the preparation of a mega-event with urban development processes that meet long-term demands. This paper examines how Beijing tried to use the Summer Olymp

  19. Beijing 2008 Olympic Games Partners

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ At Olympic times, many business giants try to expand their influence by sponsoring the Games. The Games is an opportunity for them to turn from a national to an international brand. Here are brief introductions to some of the Beijing 2008 Olympic Games partners.

  20. Search for CP and P violating pseudoscalar decays into pi pi

    NARCIS (Netherlands)

    Ablikim, M.; Achasov, M. N.; Alberto, D.; An, Q.; An, Z. H.; Bai, J. Z.; Baldini, R.; Ban, Y.; Becker, J.; Berger, N.; Bertani, M.; Bian, J. M.; Bondarenko, O.; Boyko, I.; Briere, R. A.; Bytev, V.; Cai, X.; Calcaterra, A. C.; Cao, G. F.; Cao, X. X.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, J. C.; Chen, M. L.; Chen, S. J.; Chen, Y.; Chen, Y. B.; Cheng, H. P.; Chu, Y. P.; Cronin-Hennessy, D.; Dai, H. L.; Dai, J. P.; Dedovich, D.; Deng, Z. Y.; Denysenko, I.; Destefanis, M.; Ding, Y.; Dong, L. Y.; Dong, M. Y.; Du, S. X.; Fan, R. R.; Fang, J.; Fang, S. S.; Feng, C. Q.; Fu, C. D.; Fu, J. L.; Gao, Y.; Geng, C.; Goetzen, K.; Gong, W. X.; Greco, M.; Grishin, S.; Gu, M. H.; Gu, Y. T.; Guan, Y. H.; Guo, A. Q.; Guo, L. B.; Guo, Y. P.; Hao, X. Q.; Harris, F. A.; He, K. L.; He, M.; He, Z. Y.; Heng, Y. K.; Hou, Z. L.; Hu, H. M.; Hu, J. F.; Hu, T.; Huang, B.; Huang, G. M.; Huang, J. S.; Huang, X. T.; Huang, Y. P.; Hussain, T.; Ji, C. S.; Ji, Q.; Ji, X. B.; Ji, X. L.; Jia, L. K.; Jiang, L. L.; Jiang, X. S.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Jing, F. F.; Kalantar-Nayestanaki, N.; Kavatsyuk, M.; Komamiya, S.; Kuehn, W.; Lange, J. S.; Leung, J. K. C.; Li, Cheng; Li, Cui; Li, D. M.; Li, F.; Li, G.; Li, H. B.; Li, J. C.; Li, Lei; Li, N. B.; Li, Q. J.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. N.; Li, X. Q.; Li, X. R.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Liao, X. T.; Liu, B. J.; Liu, B. J.; Liu, C. L.; Liu, C. X.; Liu, C. Y.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, G. C.; Liu, H.; Liu, H. B.; Liu, H. M.; Liu, H. W.; Liu, J. P.; Liu, K.; Liu, K.; Liu, K. Y.; Liu, Q.; Liu, S. B.; Liu, X.; Liu, X. H.; Liu, Y. B.; Liu, Y. W.; Liu, Yong; Liu, Z. A.; Liu, Z. Q.; Loehner, H.; Lu, G. R.; Lu, H. J.; Lu, J. G.; Lu, Q. W.; Lu, X. R.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Ma, C. L.; Ma, F. C.; Ma, H. L.; Ma, Q. M.; Ma, T.; Ma, X.; Ma, X. Y.; Maggiora, M.; Malik, Q. A.; Mao, H.; Mao, Y. J.; Mao, Z. P.; Messchendorp, J. G.; Min, J.; Mitchell, R. E.; Mo, X. H.; Muchnoi, N. Yu.; Nefedov, Y.; Nikolaev, I. B.; Ning, Z.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Pelizaeus, M.; Peters, K.; Ping, J. L.; Ping, R. G.; Poling, R.; Pun, C. S. J.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, X. S.; Qiu, J. F.; Rashid, K. H.; Rong, G.; Ruan, X. D.; Sarantsev, A.; Schulze, J.; Shao, M.; Shen, C. P.; Shen, X. Y.; Sheng, H. Y.; Shepherd, M. R.; Song, X. Y.; Sonoda, S.; Spataro, S.; Spruck, B.; Sun, D. H.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, X. D.; Sun, Y. J.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, X.; Tang, X. F.; Tian, H. L.; Toth, D.; Varner, G. S.; Wan, X.; Wang, B. Q.; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, Q.; Wang, S. G.; Wang, X. L.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. Y.; Wei, D. H.; Wen, Q. G.; Wen, S. P.; Wiedner, U.; Wu, L. H.; Wu, N.; Wu, W.; Wu, Z.; Xiao, Z. J.; Xie, Y. G.; Xu, G. F.; Xu, G. M.; Xu, H.; Xu, Y.; Xu, Z. R.; Xu, Z. Z.; Xue, Z.; Yan, L.; Yan, W. B.; Yan, Y. H.; Yang, H. X.; Yang, M.; Yang, T.; Yang, Y.; Yang, Y. X.; Ye, M.; Ye, M. H.; Yu, B. X.; Yu, C. X.; Yu, L.; Yu, S. P. Yu; Yuan, C. Z.; Yuan, W. L.; Yuan, Y.; Zafar, A. A.; Zallo, A.; Zeng, Y.; Zhang, B. X.; Zhang, B. Y.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, L.; Zhang, S. H.; Zhang, T. R.; Zhang, X. J.; Zhang, X. Y.; Zhang, Y.; Zhang, Y. H.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, H. S.; Zhao, Jiawei; Zhao, Jingwei; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, S. J.; Zhao, T. C.; Zhao, X. H.; Zhao, Y. B.; Zhao, Z. G.; Zhao, Z. L.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, Y. H.; Zheng, Z. P.; Zhong, B.; Zhong, J.; Zhong, L.; Zhou, L.; Zhou, X. K.; Zhou, X. R.; Zhu, C.; Zhu, K.; Zhu, K. J.; Zhu, S. H.; Zhu, X. L.; Zhu, X. W.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zou, B. S.; Zou, J. H.; Zuo, J. X.

    2011-01-01

    Using a sample of (225.2 +/- 2.8) x 10(6) J/psi events collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider, CP and P violating decays of eta, eta', and eta(c) into pi(+)pi(-) and pi(0)pi(0) are searched for in J/psi radiative decays. No significant eta, eta', or eta(c)

  1. A photon conversion finder at BESIII

    Science.gov (United States)

    Xu, Zhi-Rui; He, Kang-Lin

    2012-08-01

    A photon conversion finder (PCF) based on track information from the main drift chamber (MDC) of the Beijing Spectrometer (BESIII) at the Beijing Electron Positron Collider (BEPCII) is developed. The validation of the PCF is done by reconstructing π0 and measuring the branching fraction of J/ψ → γη'. Using the developed PCF tool, we mapped the materials from the interaction point through the BEPCII beam pipe up to the inner wall of the MDC.

  2. Measurement of the Branching Fraction for J/\\psi -> p \\bar{p}\\eta and p \\bar{p} \\eta^{'}

    OpenAIRE

    BES Collaboration

    2009-01-01

    Using 58$\\times 10^{6}$ $\\jpsi$ events collected with the Beijing Spectrometer (BESII) at the Beijing Electron Positron Collider (BEPC), the branching fractions of $\\jpsi$ to $p\\bar{p}\\eta$ and $p\\bar{p}\\etap$ are determined. The ratio $\\frac{\\Gamma(\\jpsi\\rar\\ppb\\eta)}{\\Gamma(\\jpsi\\rar\\ppb)}$ obtained by this analysis agrees with expectations based on soft-pion theorem calculations.

  3. Application of ps-streak camera in accelerator study. Measurement of longitudinal profile of electron-beam bunch

    International Nuclear Information System (INIS)

    The system for measurement of longitudinal profile of electron-beam bunch of electron accelerator with ps-streak camera has been constructed. Using this system, the length of electron-beam bunch have measured at Beijing Free Electron Laser Facility (BFEL) and Beijing Electron Positron Collider (BEPC) in Inst. of High Energy Physics of China Academy of Sciences, and Electron-Beam Injector for L-Band RF-Linac (LBINJ) in China Institute of Atomic Energy

  4. High-Power Multimode X-Band RF Pulse Compression System for Future Linear Colliders

    Energy Technology Data Exchange (ETDEWEB)

    Tantawi, S.G.; Nantista, C.D.; Dolgashev, V.A.; Pearson, C.; Nelson, J.; Jobe, K.; Chan, J.; Fant, K.; Frisch, J.; /SLAC; Atkinson, D.; /LLNL, Livermore

    2005-08-10

    We present a multimode X-band rf pulse compression system suitable for a TeV-scale electron-positron linear collider such as the Next Linear Collider (NLC). The NLC main linac operating frequency is 11.424 GHz. A single NLC rf unit is required to produce 400 ns pulses with 475 MW of peak power. Each rf unit should power approximately 5 m of accelerator structures. The rf unit design consists of two 75 MW klystrons and a dual-moded resonant-delay-line pulse compression system that produces a flat output pulse. The pulse compression system components are all overmoded, and most components are designed to operate with two modes. This approach allows high-power-handling capability while maintaining a compact, inexpensive system. We detail the design of this system and present experimental cold test results. We describe the design and performance of various components. The high-power testing of the system is verified using four 50 MW solenoid-focused klystrons run off a common 400 kV solid-state modulator. The system has produced 400 ns rf pulses of greater than 500 MW. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant line (SLED-II) pulse compression system. We also present data on the processing and operation of this system, which has set high-power records in coherent and phase controlled pulsed rf.

  5. The International Linear Collider Technical Design Report - Volume 3.II: Accelerator Baseline Design

    CERN Document Server

    Adolphsen, Chris; Barish, Barry; Buesser, Karsten; Burrows, Philip; Carwardine, John; Clark, Jeffrey; Durand, Helene Mainaud; Dugan, Gerry; Elsen, Eckhard; Enomoto, Atsushi; Foster, Brian; Fukuda, Shigeki; Gai, Wei; Gastal, Martin; Geng, Rongli; Ginsburg, Camille; Guiducci, Susanna; Harrison, Mike; Hayano, Hitoshi; Kershaw, Keith; Kubo, Kiyoshi; Kuchler, Victor; List, Benno; Liu, Wanming; Michizono, Shinichiro; Nantista, Christopher; Osborne, John; Palmer, Mark; Paterson, James McEwan; Peterson, Thomas; Phinney, Nan; Pierini, Paolo; Ross, Marc; Rubin, David; Seryi, Andrei; Sheppard, John; Solyak, Nikolay; Stapnes, Steinar; Tauchi, Toshiaki; Toge, Nobu; Walker, Nicholas; Yamamoto, Akira; Yokoya, Kaoru

    2013-01-01

    The International Linear Collider Technical Design Report (TDR) describes in four volumes the physics case and the design of a 500 GeV centre-of-mass energy linear electron-positron collider based on superconducting radio-frequency technology using Niobium cavities as the accelerating structures. The accelerator can be extended to 1 TeV and also run as a Higgs factory at around 250 GeV and on the Z0 pole. A comprehensive value estimate of the accelerator is give, together with associated uncertainties. It is shown that no significant technical issues remain to be solved. Once a site is selected and the necessary site-dependent engineering is carried out, construction can begin immediately. The TDR also gives baseline documentation for two high-performance detectors that can share the ILC luminosity by being moved into and out of the beam line in a "push-pull" configuration. These detectors, ILD and SiD, are described in detail. They form the basis for a world-class experimental programme that promises to incr...

  6. Studies of radiation hardness of MOS devices for application in a linear collider vertex detector

    International Nuclear Information System (INIS)

    The proposed International Linear Collider (ILC) together with the Large Hadron Collider (LHC) at CERN serve as a combined tool to explore the mysteries of the universe: the former is a precision machine and the latter can be considered as a finding machine. The key component of the ILC is the vertex detector that should be placed as close as possible to the Interaction Point (IP) and has better radiation tolerance against the dominant electron-positron pair production background from beam-beam interactions. A new generation of MOS-type Depleted-Field-Effect Transistor (MOSDEPFET) active pixel detectors has been proposed and developed by Semiconductor Labor Munich for Physics and for extraterrestrial Physics in order to meet the requirements of the vertex detector at the ILC. Since all MOS devices are susceptible to ionizing radiation, the main topic is focused on the radiation hardness of detectors, by which a series of physical processes are analyzed: e.g. surface damage due to ionizing radiation as well as damage mechanisms and their associated radiation effects. As a consequence, the main part of this thesis consists of a large number of irradiation experiments and the corresponding discussions. Finally, radiation hardness of the detectors should be improved through a set of concluded experiences that are based on a series of analysis of the characteristic parameters using different measurement techniques. The feasibility of the MOSDEPFET-based vertex detector is, therefore, predicted at ILC. (orig.)

  7. Dark Photon Searches Using Displaced Vertices at Low Energy e+e- Colliders

    International Nuclear Information System (INIS)

    The existence of a new, photon-like, massive particle, the γ′ or dark photon, is postulated in several extensions of the Standard Model. These models are often advocated to explain some recent puzzling astrophysical observations, as well as to solve the so far unexplained deviation between the measured and calculated values of the muon anomaly. Dark photons can be produced at e+e- colliders both in continuum events and in vector meson transitions and can eventually decay into an electron-positron pair. For a proper choice of the parameters of the theory, a γ′ can have a relatively long lifetime and can therefore be observed as an e+e- vertex well separated by the primary interaction point. This case is discussed in reference to very high luminosity e+e- colliders either in construction or under study in several laboratories in the world. It is shown that a search strategy based on the detection of displaced vertices can be in principle very effective in covering a rather wide and to date unexplored region of the theoretical parameters space

  8. Studies of radiation hardness of MOS devices for application in a linear collider vertex detector

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Qingyu

    2008-10-17

    The proposed International Linear Collider (ILC) together with the Large Hadron Collider (LHC) at CERN serve as a combined tool to explore the mysteries of the universe: the former is a precision machine and the latter can be considered as a finding machine. The key component of the ILC is the vertex detector that should be placed as close as possible to the Interaction Point (IP) and has better radiation tolerance against the dominant electron-positron pair production background from beam-beam interactions. A new generation of MOS-type Depleted-Field-Effect Transistor (MOSDEPFET) active pixel detectors has been proposed and developed by Semiconductor Labor Munich for Physics and for extraterrestrial Physics in order to meet the requirements of the vertex detector at the ILC. Since all MOS devices are susceptible to ionizing radiation, the main topic is focused on the radiation hardness of detectors, by which a series of physical processes are analyzed: e.g. surface damage due to ionizing radiation as well as damage mechanisms and their associated radiation effects. As a consequence, the main part of this thesis consists of a large number of irradiation experiments and the corresponding discussions. Finally, radiation hardness of the detectors should be improved through a set of concluded experiences that are based on a series of analysis of the characteristic parameters using different measurement techniques. The feasibility of the MOSDEPFET-based vertex detector is, therefore, predicted at ILC. (orig.)

  9. The beam energy calibration system for the BEPC-II collider

    CERN Document Server

    Achasov, M N; Mo, Xiaohu; Muchnoi, N Yu; Qin, Qing; Qu, Huamin; Wang, Yifang; Xu, Jinqiang

    2008-01-01

    This document contains a proposal of the BEPC-II collider beam energy calibration system (IHEP, Beijing). The system is based on Compton backscattering of carbon dioxide laser radiation, producing a beam of high energy photons. Their energy spectrum is then accurately measured by HPGe detector. The high-energy spectrum edge will allow to determine the average electron or positron beam energy with relative accuracy about 3x10^-5.

  10. The SLAC linear collider

    International Nuclear Information System (INIS)

    The SLAC Linear Collider has begun a new era of operation with the SLD detector. During 1991 there was a first engineering run for the SLD in parallel with machine improvements to increase luminosity and reliability. For the 1992 run, a polarized electron source was added and more than 10,000 Zs with an average of 23% polarization have been logged by the SLD. This paper discusses the performance of the SLC in 1991 and 1992 and the technical advances that have produced higher luminosity. Emphasis will be placed on issues relevant to future linear colliders such as producing and maintaining high current, low emittance beams and focusing the beams to the micron scale for collisions. (Author) tab., 2 figs., 18 refs

  11. Why Large Hadron Collider?

    Indian Academy of Sciences (India)

    D P Roy

    2011-05-01

    I discuss LHC physics in the historical perspective of the progress in particle physics. After a recap of the Standard Model (SM) of particle physics, I discuss the high energy colliders leading up to LHC and their role in the discovery of these SM particles. Then I discuss the two main physics issues of LHC, i.e. Higgs mechanism and supersymmetry. I briefly touch upon Higgs and SUSY searches at LHC along with their cosmological implications.

  12. Collide and Squeeze MD

    CERN Document Server

    Gorzawski, Arkadiusz; Papotti, Giulia; Salvachua Ferrando, Belen Maria; Wenninger, Jorg; Pieloni, Tatiana; CERN. Geneva. ATS Department

    2015-01-01

    Colliding the beams during the squeeze to profit from Landau damping due to head--on beam-beam and b* leveling are two operational modes that may have to be used in a not so distant future at the LHC. This MD aimed at improving the process control during the squeeze with much improved handling of reference for the orbit feedback system and at evaluating instruments and techniques to maintain the beam in collisions with active feedback on a good observable.

  13. The Large Hadron Collider

    CERN Document Server

    Juettner Fernandes, Bonnie

    2014-01-01

    What really happened during the Big Bang? Why did matter form? Why do particles have mass? To answer these questions, scientists and engineers have worked together to build the largest and most powerful particle accelerator in the world: the Large Hadron Collider. Includes glossary, websites, and bibliography for further reading. Perfect for STEM connections. Aligns to the Common Core State Standards for Language Arts. Teachers' Notes available online.

  14. Colliding Crystalline Beams

    International Nuclear Information System (INIS)

    The understanding of crystalline beams has advanced to the point where one can now, with reasonable confidence, undertake an analysis of the luminosity of colliding crystalline beams. Such a study is reported here. It is necessary to observe the criteria, previously stated, for the creation and stability of crystalline beams. This requires, firstly, the proper design of a lattice. Secondly, a crystal must be formed, and this can usually be done at various densities. Thirdly, the crystals in a colliding-beam machine are brought into collision. We study all of these processes using the molecular dynamics (MD) method. The work parallels what was done previously, but the new part is to study the crystal-crystal interaction in collision. We initially study the zero-temperature situation. If the beam-beam force (or equivalent tune shift) is too large then over-lapping crystals can not be created (rather two spatially separated crystals are formed). However, if the beam-beam force is less than but comparable to that of the space-charge forces between the particles, we find that overlapping crystals can be formed and the beam-beam tune shift can be of the order of unity. Operating at low but non-zero temperature can increase the luminosity by several orders of magnitude over that of a usual collider. The construction of an appropriate lattice, and the development of adequately strong coding, although theoretically achievable, is a challenge in practice

  15. The Stanford Linear Collider

    International Nuclear Information System (INIS)

    The Stanford Linear Collider (SLC) is the first and only high-energy e+e- linear collider in the world. Its most remarkable features are high intensity, submicron sized, polarized (e-) beams at a single interaction point. The main challenges posed by these unique characteristics include machine-wide emittance preservation, consistent high intensity operation, polarized electron production and transport, and the achievement of a high degree of beam stability on all time scales. In addition to serving as an important machine for the study of Z0 boson production and decay using polarized beams, the SLC is also an indispensable source of hands-on experience for future linear colliders. Each new year of operation has been highlighted with a marked improvement in performance. The most significant improvements for the 1994-95 run include new low impedance vacuum chambers for the damping rings, an upgrade to the optics and diagnostics of the final focus systems, and a higher degree of polarization from the electron source. As a result, the average luminosity has nearly doubled over the previous year with peaks approaching 1030 cm-2s-1 and an 80% electron polarization at the interaction point. These developments as well as the remaining identifiable performance limitations will be discussed

  16. STRUCTURE DESIGN OF THE BEIJING SPECTROMETER Ⅲ BEAM PIPE

    Institute of Scientific and Technical Information of China (English)

    ZHENG Lifang; JI Quan; WANG Li; LI Xunfeng; XU Shaowang; DONG Sujun; ZHAO Libin; LIU Jianping

    2008-01-01

    The Beijing spectrometer Ⅲ (BESⅢ) beam pipe is in the center of the BESⅢ, which is the detector of the upgrade project of Beijing electron and positron collider (BEPCⅡ). Electrons and positrons collide in the BESⅢ beam pipe. According to the demands of the BEPCⅡ, a key program of Chinese Academy of Sciences, the BESⅢ beam pipe is designed based on the finite elements analysis. The BESⅢ beam pipe is installed in the inner cylinder of the BESⅢ drift chamber. As a vacuum tube, the BESⅢ beam pipe is designed as 1 000 mm in length, 63 mm in inner diameter and 114 mm in outer diameter, respectively. The BESⅢ beam pipe consists of a central beryllium pipe cooled by EDM-1, the oil No.1 for electric discharge machining, and two extended copper pipes cooled by deionized water (DW). The three parts are jointed by vacuum welding. Factors taken into account in the design are as follows. ① The wall thickness of the central beryllium pipe should be designed as small as possible to reduce the multi-scattering and improve the particle momentum resolution. And the wall thickness of the extended copper pipe should be designed as large as possible to protect the detectors from the backgrounds. ② The BESⅢ beam pipe must be sufficiently cooled to avoid the damage and prevents its influence to the BESⅢ drift chamber (DC) operation. The inner surface temperature of the DC inner cylinder must be maintained at 293±2 K. ③ The magnetic permeability of the materials used in the BESⅢ beam pipe must be less than 1.05 H/m to avoid large magnetic field distortions. ④ The static pressure of the vacuum chamber of the BESⅢ beam pipe must be less than 800 (Pa. The simulating results show that the designed structure of the BESⅢ beam pipe satisfies the requirements mentioned above. The structure design scheme is evaluated and adopted by the headquarters of BEPCⅡ.

  17. Beijing Promises Event to Remember

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The host city is confident of staging a green, dope-free and stunning Olympic Games The world will remember the Beijing Olympic Games for its touching open- ing ceremony and Olympic Village with Chinese cultural elements,prom- ised key figures in the event’s preparation work at a press conference on March 12. During the annual session of the National Committee of the 11th Chinese People’s Political Consultative Conference(CPPCC),

  18. Beijing: Beyond the Olympic city

    OpenAIRE

    Chen, Y

    2012-01-01

    Mega-event strategies have become part of a deliberate urban policy for cities around the world. There is a particular concern on how to combine the preparation of a mega-event with urban development processes that meet long-term demands. This paper examines how Beijing tried to use the Summer Olympic Games 2008 to fight its spatial and environmental problems, and create a new image for the city.

  19. Singing Carmina Burana in Beijing

    Institute of Scientific and Technical Information of China (English)

    ZHANGHONG

    2005-01-01

    IN 1803 a collection of 13th century stories, poems and songs, known as the Carmina Burana, was discovered in a Bavarian monastery. The celebrated German composer Carl Orff selected various pieces from it,and transformed them into his greatestwork. On March 4 this year, Hamburg's well-known Christianeum High School Choir enthralled young Beijing musicians with their performance of this classical music.

  20. Northern Economic Hub:Beijing or Tianjin?

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The government says Tianjin, today's market suggests Beijing and some academics say the "or" is all wrong Beijing and Tianjin, the two largest cities in north China, are going through catharsis. According to the re-planning of the State Council, Beijing should shed its role as north China's economic center, and Tianjin should grow into being just that. Tianjin has long been viewed as an important economic center, but not the cen